I THE JOURNAL OF EXPERIMENTAL ZOOLOGY EDITED BY Jacques Loeb William E, Castle The Harvard University Edmund Edwin G Conklin Thomas H Morgan Columbia University Carnegie Institution S Rockefeller Institute Wilson Columbia University Princeton University Charles B Davenport Herbert B George H Parker Jennings Johns Hopkins University Harvard University Frank R Lillie Raymond Pearl University of Chicago Johns Hopkins University \ Charles R.' Stock ard Cornell University Medical College Ross G Harrison, Yale University Managing Editoi VOLUME 34 AUGUST— NOVEMBER, 1921 \ THE WISTAR INSTITUTE OF ANATOMY AND BIOLOGY PHILADELPHIA, PA CONTENTS No LiBBiE H Lyman and Albert AUGUST E Galigher Direct demonstration of the Three figures Experiments on the orientation of the ear vesicle in amphibian larvae Twenty-four figures Edward C Day The physiology of the nervous system of the tunicate II The relation of the nerve ganglion to the heart M E CoLLETT The toxicity of acids to Infusoria II The role of molecule and of ions M E CoLLETT The toxicity of acids to Infusoria III Antagonism of existence of a metabolic gradient in annelids Chikanosuke Ogawa Two the toxic action of acids by inorganic chlorides Raymond Pearl and William Freeman Schoppb ology of reproduction in the domestic fowl vations on the anatomical basis of fecundity No figures 17 45 67 75 Studies on the physiXVIII Further obser- Two 101 figures OCTOBER The relation of the pars intermedia of the hypophysis to pigmentation changes in anuran larvae Four text figures and two W W Swingle plates 119 Joseph Hall Bodine Some factors influencing the catalase content of organisms Three figures 143 S O Mast Reactions to light in the larvae of the ascidians, Amaroucium constellatum and Amaroucium pellucidum, with special reference to Ten figures The spermatogenesis photic orientation A C Walton 149 of Ascaris felis Goeze Two plates (twelve figures) Charles Zeleny 189 The direction and frequency of mutation in the bar-eye series of multiple allelomorphs of Drosophila Vasil Obreshkove The photic reactions Bunsen-Roscoe law Nine figures No 203 Five figures of tadpoles in relation to the 235 NOVEMBER Theophilus S Painter Studies in reptilian spermatogenesis I The spermatogenesis of lizards Six text figures and four plates (forty- eight figures) 281 I feTa7 CONTENTS IV LoRANDE Loss WooDRUFF Micronucleate and amicronucleate races of Four figures Hopkins The conditions 329 Infusoria HoTT S for conjugation in diverse races of Para- mecium John H Gerould Blue-green caterpillars: the origin and ecology mutation in hemolymph color in Colias (Eurymus) philodice One 339 : and one colored plate (six figures) L V Heilbrunn Protoplasmic viscosity changes during of a text 385 figure mitosis One chart Gary N Calkins E 417 Uroleptus mobilis Engelm IV Effect of cutting 449 during conjugation Ten figures LxjND Ex-perimental control of organic polarity by the electric current I Effects of the electric current on regenerating internodes of 471 Obelia commissuralis Three figures and three double plates J : PROMPT PUBLICATION The Author can in attaining greatly assist the Publishers of this Journal prompt publication paper by following these of his three suggestions Abstract Send with the manuscript an Abstract containing not more than 250 words, in the precise form of The Bibliographic Service Card, so that the paper when accepted can be scheduled for a definite issue as soon as received by the Publisher from the Editor Manuscript Send the Manuscript to the Editor prepared as described in the Notice to Contributors, to conform to the style of the Journal (see third page of cover) Illustrations Send the Illustrations in complete and fin- ished form for engraving, drawings and photographs being protected from bending or breaking when shipped by mail By assuming and or express meeting these responsibihties, the author may be required to get the Abstract, Manuscript and Illustrations in proper form, and avoids loss of time, correspondence that does all in his power to obtain prompt publication THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL 34, NO 1, AUGUST, 1921 Resumen por los autores Demostracion directa de Libbie H Hyman y la existencia en Albert E Galigher de un gradiente metabolico los anelidos Por medio de la susceptibilidad y de los metodos electricos los han acumulado pruebas que indican claramente la existencia de un gradiente matabolico doble en los anelidos oligoquetos y poliquetos Segun estas pruebas, los extremos autores " anterior y posterior poseen la mayor proporci6n metab61ica, la cual decrece a partir de dichos extremos hacia las regiones medias; en la mayor parte de las formas el extremo posterior posee mayor proporcl6n metab61ica que el anterior En el presente trabajo los autores dan a conocer determinaciones directas de la proporcion de oxigeno consumido por unidad peso de trozos de las regiones anterior, media y posterior del oligoqueto Lum- y de los poliquetos Nereis virens y Nereis Los resultados de estas determinaciones son que los trozos posteriores de estas especies consumen mas oxigeno por unidad peso durante unidad tiempo, mientras que los trozos de la region anterior consumen menos y los de la media la menor cantidad Los resultados, por consiguiente, confirman las conclusiones derivadas de los otros metodos y establecen de un modo indudable la existencia de un gradiente metab61ico doble en estas briculus inconstans vexillosa formas Translation by Jos6 F Nonidez Cornell Medical Collese, New York AUTHOR S ABSTRACT OF THIS PAPER ISSUED BY THE BIBLIOGRAPHIC SERVICE JUNE 27 DIRECT DEMONSTRATION OF THE EXISTENCE OF A METABOLIC GRADIENT IN ANNELIDS LIBBIE H HYMAN AND ALBERT E GALIGHER Hull Zoological Laboratory, University of Chicago THREE FIGURES INTRODUCTION For a number of years evidence has been presented from this laboratory concerning the existence of metaboUc gradients in organisms several of follows This evidence has been obtained through the use methods These may be summarized briefly as ^ : Regeneration method In pieces cut from different levels of the axis of simple organisms the rate of regeneration and the kind of structure regenerated exhibit graded differences correThese lated with the level from which the pieces are taken phenomena differences in the regenerative at different levels cannot be due primarily to morphological factors, but are functional in nature, since they depend upon the size of the piece and are easily alterable by conditions whose action is chiefly quantitative !2 Direct susceptibility method Different levels of the axis of simple organisms exhibit a differential susceptibility to con- centrations of toxic substances which will kill within a few hours Since the death gradients of organisms in such solutions are the same for a large variety of toxic substances of widely different chemical constitution, these gradients solely to the specific mode cannot be due but of action of these substances, must depend rather upon a general quantitative gradation of some sort existing within the organism itself The susceptiFor a more complete discussion of these methods together with references consult Child ('20) ' LIBBIE H method HYMAN AND ALBERT GALIGHER E used to control morphogenesis during For this purpose less concentrated This solutions are employed which not kill, but depress bility is also regeneration or development depression is differential; consequently, when regenerating pieces embryos are exposed to the proper concentrations, morphological modifications result which are predictable and That difexplicable on the basis of the susceptibility gradient or eggs or ferential susceptibility to toxic solutions is correlated ferences in metabolic rate is shown by the with dif- fact that conditions which are known to modify metabolic rate also modify susceptibility and in the same direction Indirect susceptibility The death gradient method of organ- isms in dilute concentrations of toxic substances such that death occurs only after several days' exposure is exactly the opposite of the death gradient in quickly lethal solutions This shows that the susceptibility due to differential would be impossible to ac- results are not permeability, since in that case it count for the difference in the action of solutions of different concentration tions ential The reversal of the gradients in dilute solu- believed to be due to differential acclimation is acclimation also accounts for certain Differ- modifications induced during regeneration and development exposure to the proper concentrations of toxic substances When organisms are Indophenol method exposed to a dimethyl-p-phenylene-diamine and a-naphthol a It is generally blue precipitate of indophenol is produced accepted that the formation of this precipitate depends upon The depth of color the presence of oxidative processes mixture of produced along the axes of organisms through this reaction exhibits the same gradation as evidenced by the direct susceptibility and other methods This method has been used only for embryonic stages and small forms When exposed to solu0 Potassium permanganate method tions of potassium permanganate organisms reduce it to manganese dioxide The capacity to carry out this reduction exhibits the same gradation along the axis as appears by other methods METABOLIC GRADIENT IN ANNELIDS With the aid of a galvanometer it Electrical melhods found that permanent differences of potential exist along the These electrical gradients correspond to the axes of animals is and reduction susceptibility, staining, highest susceptibility, greatest gradients, the regions of and reducing powers staining, being electronegative (galvanometrically) susceptibility, staining, to regions of lower and reducing powers behavior of at least the simpler organisms is The galvanotactic also in accord with the metabolic gradient conception The concordance indicates clearly of results obtained of a definite gradation The nature of this gradation is Our explanation that the grada- along the axes of organisms naturally open to discussion tion by these various methods enough the existence primarily quantitative involving differences in the rate is fundamental metabohc reactions and in conditions associated with these is the only one that fits all of the facts at present of known It bolic to to us would obviously be desirable, in order to establish the nature of the gradients make beyond all meta- reasonable doubt, quantitative tests of the rate of metabolism of different To levels of the axis so would appear to be a relatively number of complicating factors place we must consider whether the simple matter, but in fact a In the are involved first from isolation of pieces different levels involves physiological changes in the pieces We have definitely shown for Planaria that it does involve considerable metabolic increase, and that this increase is related quantitatively to the length of the pieces and the level of the nate this factor it is body from which they are taken To elimi- necessary either to cut pieces so long that the stimulation of cutting is reduced to a minimum or to wait until the stimulation has disappeared, as happens after a number of In the former case an organism of sufficient length would have to be selected; in the latter case one encounters changes due to the onset of regeneration It is further necessary to select organisms which present neither structural nor special functional hours differences along their axes specific part may The functional activity of some not accord with the general gradient, and LIBBIE H HYMAN AND ALBERT GALIGHER E determinations of the total metabolism of such parts might therefore give results seemingly at variance with the gradient concep- The tion gradients of particular organs or structures are not necessarily the of many same as those of the organism in general instances of such secondary gradients ; we know Selection of the proper organism and elimination of these complicating factors are therefore essential before determinations of the total metabolism of isolated pieces possess On it is any meaning thinking over the organisms available for such experiments, obvious that they are few in number only under carefully controlled conditions Planarians are usable Under such control has already been shown that the carbon-dioxide production at different levels of the anterior zooid corresponds with the gradient it conception (Robbins and Child, '20), and similar experiments on the oxygen consumption are now in progress Certain hydroids could probably be used, and experiments on them will be undertaken as soon as opportunity affords The annelids are, however, by far the most suitable organisms for this kind of experimentation Among the annelids there are many forms which are morphologically much the same throughout the greater part of the body in the sexually immature condition They are, moreover, long enough to permit the cutting of pieces of the length necessary to eliminate the stimulation of section As far as we have been able to determine, there are, in the non-sexual state, no special regions having a rate of activity different from that of the body in general The susceptibility the gradient of the digestive tract is method has shown that the same as that of the body By means of methylene blue the gradient of the nervous wall system has likewise been determined to be of the same character.^ In these animals, then, there is every reason to predict that pieces cut from different levels of the body will show differences in respiratory rate which will accord with the susceptibility differ2 In making a previous note on the use of methylene blue for demonstrating minor gradients (Jour Exp Zool., vol 24, p 55), the senior author, being at that time ignorant of the fact, failed to credit Mr John Wood jMacArthur, formerly of this laboratory, with precedence in the use of this reagent, and takes this opportunity of correcting that omission CONTROL OF ORGANIC POLARITY By a careful study of these drawings the following facts appear 483 : The greater the current density the greater the inhibition This occurs to a lesser extent in the end which happens to be turned toward the anode than in that turned toward the cathode There is a lower current density, branch I, below which regeneration takes place in practically a normal manner It should be noted that in branch I the regeneration at the apical end of all the internodes preceded that at the basal end; i.e., of regeneration overcome the inherent polarity of the the electric current did not This means that with respect to the effect of the current there is something which is similar to a threshold Compare the orientation of Paramecium in an elecdensity pieces in branch I tric current Regeneration on the end toward the cathode, branches II, also IV, is inhibited to a greater degree (if not completely) than regeneration on the end toward the anode, irrespective of whether the apical or basal end of the internode is III, and pointed toward the cathode 4: The density of the electric current necessary (delay) regeneration in apical internodes is to inhibit greater than that necessary for inhibition of regeneration in more basal internodes of the same branch That bition of apical internodes is, is the threshold density for inhi- higher than for basal internodes, other conditions being the same This statement corresponds to the fact that apical internodes in the absence of the current more basal internodes of the same branch was practically normal in its regeneration and might regenerate sooner than Branch I as a matter of fact serve as a control for the results in branches II, III, The and IV result in this experiment does not differ from that in experiment I, for if we had selected internodes from the level of branches corresponding to that of the middle region of branch III for example, and left them to regenerate for forty-five hours instead of thirty-four hours then same results we should have expected the 484 E J LUND and were discontinued before it was possible what regenerative processes, if any, would finally have occurred in ends toward the cathode and those turned toward the anode, which showed no regeneration For this reason experiment was repeated Experiynent The current density was slightly greater Experiments to decide than in experiment This is also clearly evident when the results in branch I, experiment 2, is compared with branch I The material was obtained from vigorous in this experiment Duration of the growing colonies on the laboratory float experiment was sixty-six hours, thus allowing time enough for regeneration of stolons, if these would develop in the pieces Observations were made at intervals throughout the experiment At thirty-one hours the difference in growth between ends toward the anode on basal and apical internodes was very clearly shown in branches I, II, and III A very much greater growth occurred toward the anode than toward the cathode in the same branches Only traces of growth, if any, appeared in branch IV The greater orienting effect of the stronger current in this experiment was plainly e\ddent when compared to that in experiment at the same interval At the end of sixty-six hours (plate 3, A, B), branch IV in relative current density of shows practically complete mhibition Only two immature pol\T)s had at both ends of the internodes developed on apical ends toward the anode, which without the current would have reached full development in less than forty Two undeveloped stolons appeared at ends toward the hours cathode Branch III regenerated stolons on all internodes which showed any appreciable growth on the cathode end Hydranths formed only on the anode ends of the pieces, and apical internodes in general developed hydranths earher same branch than This therefore shows that, irrespective of whether the basal or apical end of the internode is turned toward the anode, stolons can develop on the end toward the cathode basal internodes of the CONTROL OF ORGANIC POLARITY 485 In branch II thirteen internodes formed stolons on ends toward the cathode, nine showed no growth toward the cathode, within sixty-six hours, while only one internode from the apical end formed a hydranth toward the cathode Again no stolons formed toward the anode In branch I no stolons formed Hydranths were more numerous on the anode than on the cathode side, showing a marked orienting effect of the current However, the current was not strong enough to bring ^about any growth of stolons, on cathode end, instead of hydranths, within the limit of sixtysix hours In removing the pieces of branches II and III, most of the off, because of their attachment to the Hence they are not shown complete in side of the cork plate the drawings Pieces of cork are shown attached to some of the stolons were broken stolons The important confirming all which fact this experiment shows besides the previous statements is that inhibition of hy- dranth formation at the cathode in a suitable current density does not mean that the capacity of this tissue to the tissue can and does grow differentiate into is lost, but rather that a stolon which functions normally, and this occurs irrespective of the original orientation have therefore fulfilled the of the internode in the current We second requirement for a proof, page 479 above, that an electric current of proper density can reverse the inherent polarity of an internode the piece and determine according to the direction which of the physiological axis in morphological development and differentiation take place It might be supposed that light played a part in determining the orientation, since growth in some hydroids shows a directive effect due to in the result branch light, e.g., is Eudendrium That light plays evident from the control in experiment no part 1, also experiment Other experiments showed clearly that light did not enter into the experiment as a directive factor The possible directive effect of the water current is ruled out for the I in same reasons as those for light : 486 E J LUND Without proper test, it might be assumed that the difference between the appearance of hydranths on the apical and basal internodes of the same branch, experiments and 3, were due to a difference in current density on the two sides of the gradient trough, one side of the water column being thicker than the other This objection is removed by the fact that the serial apicobasal order of the internodes of branch I, experiment 3, was purposely inverted, yet the earlier observations during the experiment showed clearly that hydranths developed earlier on apical than on basal internodes Furthermore, in experiment 1, apical internodes showed earher development than slightly more basal internodes, even though no serial order was maintained Finally, measurements of the thickness A similar of two sides of the trough showed no difference reasoning would seem to rule out contact stimulus as a in the time determining factor Several experiments not as comprehensive as those presented and in which fewer internode pieces were used confirm all drawn from the experiments presented above Many questions, of course, remain to be answered, some of which will be considered in following The above experiments constitute, therefore, onlj^ a papers hopeful beginning of the analysis of the problem of polarity by means of this method Under the conditions of the olDservations the following conclusions may be drawn the observations and conclusions to be SU^IMARY Internodes cut from Obelia commissuralis possess and retain an inherent polarity, according to which regeneration of a hydranth occurs at the apical end before that at the basal end of the internode Apical internodes develop hydranths nodes of basal origin earlier than inter- With an appropriate density of electric current, all hydranth formation on ends of internodes when turned toward the cathode can be delayed or entirely inhibited, while at the same time hydranths may form in a high percentage of pieces on ends pointed toward the anode CONTROL OF ORGANIC POLARITY Under conditions in 3, stolons may 487 regenerate and function normally on ends toward the cathode Statements under and hold for pieces irrespectively of whether basal or apical end of an internode is pointed toward the anode; that is, the inherent normal polarity of the inter- node may be reversed by means of an electric current A current density barely able to inhibit regeneration in basal internodes cannot inhibit regeneration in apical inter6 nodes of the same branch The estaUishment of an electrochemical polarity is probably a primary, fundamentally associated condition for the development of morphological polarity, because the physiological mechanism which determines morphological polarity can be controlled and directed by an electric current of external origin CONTROL OF ORGANIC POLARITY E J LUND ^^^^^^3 CONTROL OF ORGANIC POLARITY E J l^^iSaaSi LUND i^^ CONTROL OF ORGANIC POLARITY E.J LUND Apical Current Current density/^ density^ Branch Branch I Basal 490 II CONTROL OF ORGANIC POLARITY E J LUND Apicsd Current density J^ Current density ^^3^^^ ^^r:^'^:''TrrT:^Z:j:r'-rr',:^ Branch Branch Basal 491 IV CONTROL OF ORGANIC POLARITY E J LUND Ap'iczxl Current Current density J^ Branch Branch I Basal 492 density J;^ II CONTROL OF ORGANIC POLARITY E J LUND ApiICQl Current density Current densily /2 (fii^^^^^g) ^^^3m ^ Branch Branch lY HI Basal 493 SUBJECT AND AUTHOR INDEX ACIDS cule and of ions to Infusoria Acids to Infusoria II The III toxic action of acids The toxicity of by The role of moletoxicity of 67 Color in Colias (Eurymus) philodice Bluegreen caterpillars: the origin and ecology of a mutation in hemolymph 385 Commissuralis Experimental control of organic polarity by the electric current I Effects of the electric current on regenerating interiiodes of Obelia 471 Antagonism of the inorganic chlorides 75 Allelomorphs of Drosophila The direction and frequency of mutation in the bar-eye series of multiple Conjugation in diverse races 203 The Amaroucium constellatum and Amaroucium , to Infusoria Ill relation 119 heart Domestic BAR-EYE series of multiple allelomorphs of Drosophila The direction and frequency of mutation in the 203 Blue-green caterpillars: the origin and ecology vesicle Ecology 143 Bunsen-Roscoe law 235 CALKINS, G.\RT N Uroleptus mobilis Engelm IV Effect of cutting during conjugation 449 Catalase content of organisms Some factors influencing the Caterpillars: the origin and ecology of a mutation in hemolymph color in Colias (Eurymus) philodice Blue-green Changes during mitosis Protoplasmic viscosity Chlorides The toxicity of acids to Infusoria III Antagonism of the toxic action of acids by inorganic Colias (Eurymus) philodice Blue-green caterpillars: the origin and ecology of a mutation in hemolymph color in CoLLETT, M E The toxicity of acids to Infusoria II The role of molecule and of ions CoLLETT, M E The toxicity of acids to Infusoria III Antagonism of the toxic action of acids by inorganic chlorides 471 471 of the The the nerve ganglion to the XVIII Further Experi17 a mutation in hemolymph color in Colias (Eurymus) philodice Bluegreen caterpillars: the origin and 385 Electric current I Effects of the electric current on regenerating internodes of Obelia commissuralis Experimental control of organic polarity by the 471 factors influ 149 45 fowl in amphibian larvae EARments on the orientation of the a mutation in hemolymph color in Colias (Eurymus) philodice 385 of Some of 449 observations on the anatomical basis of fecundity Studies on the physiology of reproduction in the 101 Drosophila The direction and frequency of mutation in the bar-eye series of multiple allelomorphs of 203 encing the catalase content of organisms The photic reactions of tadpoles in relation to the 339 II Ascaris felis Goeze The spermatogenesis of 189 Ascidians, Amaroucium constellatum and Amaroucium pellucidum, with special reference to photic orientation Reactions to light in the larvae of the 149 BoDiNE, Joseph Hall Paramecium Edward C The physiology DAY, nervous system of the tunicate 75 Anuran larvae The relation of the pars intermedia of the hypophysis to pigmentation changes in of conditions for Conjugation Uroleptus mobilis Engelrn IV Effect of cutting during Constellatum and Amaroucium pellucidum, with special reference to photic orientation Reactions to light in the larvae of the ascidians, Amaroucium Control of organic polarity by the electric current I Effects of the electric current on regenerating internodes of Obelia commissuralis Experimental Current I Effects of the electric current on regenerating internodes of Obelia commissuralis Experimental control of organic polarity by the electric pellucidum, with special reference to phoReactions to light in the tic orientation 149 larvae of the ascidians Amaroucium pellucidum, with special reference to photic orientation Reactions to light in the larvae of theascidians.Amaron149 cium constellatum and Amicronucleate races of Infusoria Micro329 nucleate and _ Amphibian larvae Experiments on the orientation of the ear vesicle iii 17 Annelids Direct demonstration of the existence of a metabolic gradient in Antagonism of the toxic action of acids by inorganic chlorides The toxicity of acids ot FECUNDITY of Studies on the physiology reproduction in the domestic fowl XVIII Further observations on the anatomical basis of 101 Felis Goeze The spermatogenesis of Ascaris 189 Fowl XVIII Further observations on the anatomical basis of fecundity Studies on the physiologj- of reproduction in the domestic 101 143 385 417 GALIGHER, 75 385 67 75 495 Albert E., Hyman, LibBiE H., AND Direct demonstration of the existence of a metabolic gradient in annelids Ganglion to the heart The physiology of the nervous system of the tunicate II The relation of the nerve 45 Gerould, John H Blue-green caterpillars: the origin and ecology of a mutation in hemolymph color in Colias (Eurymus) philodice 385 496 ganglion to the heart The physiNERVE ology of the nervous system of the tuni- The phj'siology of the nervous HEART system of the tunicate II The rela- cate II The relation of the of the tunicate II relation of the nerve ganglion to heart The physiology of the 45 tion of the nerve ganglion to the L V Protoplasmic viscosity 417 changes during mitosis Hemolymph color in Colias (Eurymus) philodice Blue-green caterpillars: the 385 origin and ecology of a mutation in Hopkins, Ho^t S The conditions for con339 jugation in diverse races of Paramecium Htman, Libbie H., and Galigher, Albert E Direct demonstratioii of the existence of a metabolic gradient in annelids Hypophysis to pigmentation changes in anuran larvae The relation of the pars Heilbrunn, Nervous system OBELIA commissuralis 119 intermedia of the Micronucleate and amicro- 329 nucleate races o Infusoria ions II The The role of molecule and of toxicity of acids to 67 Infusoria III Antagonism of the toxic action of acids by inorganic chlorides The toxicity of acids to 75 Internodes of Obelia commissuralis Experimental control of organic polarity by the electric current I Effects of the electric 471 current on regenerating The toxicity of acids to Infusoria The role of molecule and of Ions II ._ LARVAE Experiments on the orientation of the ear vesicle in amphibian Larvae of the ascidians, Amaroucium constellatum and Amaroucium pellucidum, with reference to photic orientation Reactions to light in the Larvae The relation of the pars intermedia the hypophysis to pigmentation of changes in anuran Law The photic reactions of tadpoles in relation to the Bunsen-Roscoe Light in the larvae of the ascidians, Amaroucium constellatum and Amaroucium pellucidum, with special reference to photic orientation Reactions to Lizards Studies in reptilian spermatogenesis I The spermatogenesis of Lund, E.J Experimental control of organic polarity by the electric current I Effects of the electric current on regenerating internodes of Obelia commissuralis 67 17 MAST, 149 119 235 149 281 471 Reactions to light in the larvae of the ascidians, Amaroucium constellatum and Amaroucium pellucidum, with special reference to photic changes viscosity Protoplasmic 417 during Mobilis Engelm IV Effect of cutting dur449 ing conjugation Uroleptus Molecule and of ions The toxicity of acids Mitosis The 67 role of Multiple allelomorphs of Drosophila The direction and frequency of mutation in 203 the bar-eye series of to Infusoria I Mutation in hemolymph color in Colias (Eurymus) philodice Blue-green cater385 the origin and ecology of a Mutation in the bar-eye series of multiple allelomorphs of Drosophila The direc203 tion and frequency of pillars: latum and Amaroucium pellucidum, with 149 special reference to photic Origin and ecology of a mutation in hemolymph color in Colias (Eurymus) philo385 dice Blue-green caterpillars: the Theophilus S Studies in The I reptilian spermatogenesis 281 spermatogenesis of lizards Paramecium The conditions for conjugation 339 in diverse races of Pars intermedia of the hypophysis to pigmentation changes in anuran larvae The 119 relation of the domestic fowl reproduction in the XVIII Further observations on the ana101 tomical basis of fecundity Pellucidum, with special reference to photic orientation Reactions to light in the larvae of the ascidians, Amaroucium 149 constellatum and Amaroucium Philodice Blue-green caterpillars: the origin and ecology of a mutation in hemolymph (Eurymus) 385 Photic orientation Reactions to light in the larvae of the ascidians, Amaroucium constellatum and Amaroucium pelluci149 dum, with special reference to Photic reactions of tadpoles in relation to the Bunsen-Roscoe law 329 Infusoria the orientation of the ear vesicle in amphibian larvae 17 Organic polarity by the electric current I Effects of the electric current on regenerating internodes of Obelia commis471 suralis Experimental control of Organisms Some factors influencing the 14 catalase content of Orientation of the ear vesicle in amphibian larvae Experiments on the Orientation Reactions to light in the larvae of the ascidians, Amaroucium constel- color in Colias 149 orientation Ogawa, Chikanosuke Experiments on Pearl, Raymond, and Schoppe, William Freeman Studies on the physiology of O annelids Direct in Metabolic gradient demonstration of the existence of a Micronucleate and amicronucleate races of 45 Experimental con- PAINTER, special S the trol of organic polarity by the electric current I Effects of the electric current on regenerating internodes of 471 Obreshkove, V.a-Sil The photic reactions of tadpoles in relation to the Bunsen235 Roscoe law INFUSORIA 45 The The Phvsiologv of reproduction in the domestic fowl XVIII Further observations on the anatomical basis of fecundity Studies on the Physiology of the nervous system of the tunicate II The relation of the nerve ganglion to the heart The Pigmentation changes in anuran larvae The relation of the pars intermedia of the hypophysis to Polarity by the electric current I Effects of the electric current on regenerating commissuralis Obelia of internodes Experimental control of organic Protoplasmic viscosity changes during mitosia 235 101 45 119 471 417 INDEX REACTIONS of tadpoles in relation to the 235 Bunsen-Roscoe law The photic Reactions to light in the larvae of the ascidians, Amarouciuni constellatum and Amaroucium pellucidum, with special 149 reference to photic orientation Regenerating intcrnodes of Obelia commisExperimental control of organi suralis electric current I Efpolarity by the 471 fects of the electric current on Reproduction in the domestic fowl XVIII Further observations on the anatomical basis of fecundity Studies on the physiology of 101 Reptilian spermatogenesis I The spermato281 genesis of lizards Studies in _ 497 TADPOLES relation to the Bunsen- in The photic Roscoe law UROLEPTUS William Freeman, Peabl, Raymond, and Studies on the physiology of reproduction in the domestic XVIII Further observations on 101 the anatomical basis of fecundity Spermatogenesis of Ascaris felis Goeze The 189 Spermatogenesis I The spermatogenesis of lizards Studies in reptilian 281 Swingle, W W The relation of the pars intermedia of the hypophysis to pigmen119 tation changes in anuran larvae fowl mobilis Engelm IV during conjugation 235 67 75 45 Ef- fect of cutting 449 VESICLE in amphibian larvae Experiments on the orientation of the ear changes plasmic Viscosity SCHOPPE, reactions of Toxicity of acids to Infusoria II The role of molecule and of ions The Toxicity of acids to Infusoria III Antagonism of the toxic action of acids by inorganic chlorides The Tunicate 11 The relation of the nerve ganglion to the heart The physiology of the nervous svstem of the A C WALTON, Ascaris felis during mitosis 17 Proto417 The spermatogenesis of Goeze 189 Woodruff, Lorande Loss Micronucleate and amicronucleate races of Infusoria 329 ZELENY, Charles The direction and frequency of mutation in the bar-eye series of multiple allelomorphs of phila Droso203 ... relation of the nerve ganglion to the heart M E CoLLETT The toxicity of acids to Infusoria II The role of molecule and of ions M E CoLLETT The toxicity of acids to Infusoria III Antagonism of existence... individuals give evidence of the existence of a breaking In figure level are presented graphs of the death gradients of three individuals of Lumbriculus inconstans in solutions of potassium In constructing... the new segments individuals above; in number of in front of the anal segment All three of the show the presence of the zone of autotomy described two of them this zone is well marked, while in