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THE REACTIONS OF CERTAIN CLADOCERA TOCOLORED LIGHTS OP EQUAL INTENSITY.
HYMAN LUMER,Western Reserve University.
I. INTRODUCTION.
It is well known that cladocera are, at most times, sensitiveto light. This fact has given rise to a number of investigationson the relative sensitivity of these animals to light of differentwave-lengths.
Experiments of this nature were first performed by Bert(1869). He exposed Daphnia to light from different portionsof an electric light spectrum, and found that the animalsgathered most rapidly in the green and yellow-green, althoughthey were positive to all colors. Similar results were obtainedby Lubbock (1881), Hess (1910), Loeb and Maxwell (1910),Ewald (1914), and Borowski (1927). All these investigatorsused colored lights produced by a prismatic spectrum, althoughLubbock and Ewald also employed colored filters.
Yerkes (1900) found that Simocephalus vetulus gathered inthe yellow of a Welsbach burner prismatic spectrum, but thatwhen a triangular prism containing India ink was placed betweenthe source of light and the animals, so that the intensity of thered end of the spectrum was cut down to a much greater extentthan that of the violet, they tended to aggregate in the blueand violet.
v. Frisch and Kupelweiser (1913), working with Daphnia,found that the animals, which became negative when the lightintensity was decreased, and positive when it was increased,were positive to green, yellow, and red, although the intensitywas raised, and negative to violet, blue, and blue-green, althoughthe intensity was decreased. Similarly, Becher (1921), usingcolored solutions, found that Daphnia magna was positive togreen, yellow, and red, and negative to blue and violet. Koehler(1921) obtained similar results with isolated portions of aprismatic spectrum.
Peters (1926), using a method similar to that of Becher,carried out investigations on a number of species of cladocera.For most of the species he obtained results similar to Becher's.
218
No. 3 LIGHT REACTIONS OF CLADOCERA 219
Scapholeberis mucronata and Peracantha truncata, on the otherhand, were found to be positive to blue and negative to othercolors.
The results obtained by these investigators agree fairly-well, but their methods are, in certain respects, subject tocriticism. In most cases the apparatus was neither standard-ized nor calibrated. Various sources of light were used. Oftenthe wave-length transmissions of the colors used were notknown. The most common fault was that of ignoring theeffect of intensity, and ascribing the effects of colors to wave-length alone.
In order to ascertain quantitatively the relative stimulatingeffect of different wave-lengths on an organism, it is necessaryto eliminate any effects which may be due to differences inintensity, either by making a correction in the results for suchdifferences (Mast, 1917), or by using colors of equal intensity(Visscher and Luce, 1928). In none of the experiments oncladocera were either of these methods used.
The present investigation was undertaken with the objectof making a comparative study of the stimulating effect ofcolored lights of equal intensity on certain species of cladocera.
The author is indebted to Dr. J. P. Visscher, who suggestedthis investigation, for his helpful suggestions and advice duringthe course of the work.
II. MATERIALS AND METHODS.
1. Selections of animals for experiments:Investigations were carried out on" the following four
species: Daphnia pulex, Daphnia magna, Moina brachiata andLeptodora kindtii.
Daphnia pulex and Moina brachiata were collected in pondsin the vicinity of Cleveland. They were raised in the laboratoryin a culture medium made up of unicellular forms of algaegrowing in Moore's solution, which was made up according tothe following formula:
Distilled water 1 literNH4NO3 0.5 gms.KH2PO4 0.2 "MgSO4 0.2 "CaC12 0.1 "Pe SO4 (1% soln.) 10 minims
The formula for this culture medium was taken, with somemodification, from one originally used by Klugh (1927).
220 HYMANLUMER . Vol. X X X I I
It is well known that the cladocera normally reproduceparthenogenetically. The eggs are laid in a brood chambersituated between the carapace and dorsal body wall. Herethey remain until they are released, producing young animalswhich are like the adults in appearance. Consequently, itwas an easy matter to obtain animals which were not onlyof the same age, but also alike in genetic constitution. Theproceedure was as follows: The individuals of a single broodof young were isolated. When these reached maturity, andproduced young, the successive broods were separated. Thesewere used in experiments within twenty-four hours after thefirst brood had been released. Only females were used, themales being discarded in the few instances in which theyoccurred.
Specimens of Daphniamagna were obtained from a clonederived from a stock kept by Banta at Brown University, andwere grown in a manure infusion, made by steeping manurein tap water for a few days, and then straining through severallayers of cheesecloth (Banta, 1921). Animals were selected foruse in experiments in the same manner as with Daphnia pulexand Moina brachiata.
The work on Leptodora kindtii was done at Franz TheodoreStone Laboratory, at Put-in-Bay, Ohio, in the first week ofAugust, 1931. This species was fairly numerous in bottomtows made in the lake with a number twelve mesh tow net.It was found that the animals could not be kept in the laboratoryfor more than two or three days, so collections were madeevery morning, and the animals used the same day. Onlyadult females were used; these could be readily distinguishedby the presence of a brood chamber.
It is desirable, during the course of experiments with coloredlights, to keep the animals in a colorless culture medium.Since the medium used for Daphnia pulex and Moina brachiatawas slightly green in color, and that used for Daphnia magnawas brown, it was necessary to transfer the animals to anothermedium. A satisfactory one was obtained by filtering theoriginal algal medium, so that practically all the algae wereremoved. To this the animals were transferred several hoursbefore the experiment. For Leptodora, filtered lake waterwas used.
Although the animals grown in the laboratory were notkept at a constant temperature, their growth-rate was fairly
No. 3 LIGHT REACTIONS OF CLADOCERA 221
constant. Daphnia pulex released the first brood of young inseven to eight days, Moina brachiata in five to six days, andDaphnia magna in twelve to thirteen days. The temperatureat which the experiments were performed varied between19.5° C. and 21.5° C. The temperature of the dark room usedin the work with Leptodora kindtii was somewhat higher,varying between 25.5° C. and 26.5° C.
2. Apparatus:The apparatus used in these experiments is essentially
the same as that used by Visscher and Luce (1928). In fact,the lamps and filters used in this work, which were generouslyloaned to me by Dr. J. P. Visscher, are the identical ones usedin their investigations. Since these are fully described in theirpaper, only a brief description will be given here.
Thirteen filters were used, of which eight were Corningglass filters, and five Wratten filters. They are listed inTable I, together with their spectral transmissions, dominantwave-lengths, and relative energy transmissions, as given bythe distance at which the lamp must be placed for each filterto make the energies equal.
It will be noted that the first three filters in the seriestransmit some red. It is impossible to obtain a filter for theultra-violet end of the spectrum, which does not transmit somered. There is no way of blocking out this red, without alsoblocking out some of the blue or ultra-violet. Since the amountof red transmitted is relatively small, it was decided best touse the filters as they were, and attempt a correction for thered later. This correction was made by determining thepercentage of red transmitted, and deducting that from thetotal value obtained in the experiments.
The lamp used was a 100 watt, 115 volt, gas filled Mazdalamp, which carried, during experiments, the regular citycurrent of 110 volts. The infra-red rays were absorbed by acopper sulfate filter two centimeters thick, and filled with asolution consisting of 57 grams of copper sulfate in two litersof water.
The apparatus was set up as shown in Figure 1. The lampwas enclosed in a light-proof box, with an opening about 5centimeters in diameter. A copper sulfate cell was placed infront of the opening. The box was movable, and mounted ona track. The aquarium in which the animals were placed
222 HYMAN LUMER Vol. XXXII
was 40 millimeters square, and 20 millimeters deep, and madeof a high grade of slide glass, cemented together with De-Khotinsky cement. A line was marked across the bottom,dividing it into halves, one half toward the source of light,the other away from it. The aquarium was mounted on astand containing a small microscope lamp, which could be usedto light the aquarium from below, thus facilitating the countingof the animals. Between the lamp and the aquarium was
4
-s
FIGURE 1. Diagrams to illustrate the apparatus used in the experiments. T,track for box (B) containing lamp (L). C, copper sulphate filter in front ofopening in box. S, screen holding filters (E). F, aquarium stand containingmicroscope lamp (I/)- A, aquarium.
placed a screen, containing an opening 5 centimeters in diameter,and a slot for the filters. The screen, stand, and lamp boxwere covered with heavy black paper, and the entire apparatusset up in a dark room.
3. Method:When exposed to white light, Daphnia pulex and Moina
brachiata were found to be neutral, and Daphnia magna andLeptodora kindtii negative. It was found, however, that theybecame positive when exposed to certain monochromatic lights.The method used in the experiments is based on this observation.
No. 3 LIGHT REACTIONS OF CLADOCERA 223
In carrying out an experiment, a number of animals from asingle brood, usually about ten, were placed in the aquarium,and left for several hours in the dark room, to allow them tobecome dark adapted. They were then exposed to light.They were given three exposures of one minute each (twominutes in the case of Daphnia pulex) to each filter, with the
TABLE I.*
LIST OF FILTERS USED, SHOWING THEIR TOTAL SPECTRAL TRANSMISSION, DOMINANTWAVE-LENGTHS, AND THE DISTANCE OF LAMP FROM AQUARIUM FOR EACH.
Filter
Ultra C83
Purple C69
Purple W35
Blue W49BlueC60Blue C59Blue-green C56Green C52Green W58Yellow W15Orange W22Orange C38Red C19White Light
• TotalTransmission
315-428 fifi609-Red End
310-485 ^690-Red End
300-475 ^650-700 IX/JL
400-510 ^335-640 nn335-690 nn340-700 ^425-670 nix485-635 fin500-700 fiut545-700 nn540-Red End620-Red End
DominantWave-Length
3 5 5 MM
370 MM
420 MM
440 MM4 6 0 MM480 MM505 nn5 3 0 MM540 MM590 MM6 2 0 MM640 MM700 MM
Distance of Lampfrom Aquarium
24.9 cm.
42.4 cm.
44.4 cm.
52.6 cm.81.5 cm.93.2 cm.
100 cm.65.6 cm.63.2 cm.
102.3 cm.83.0 cm.77.3 cm.49.2 cm.
119.2 cm.
The letter " C " after a filter denotes a Corning glass filter. The number afterthe Corning Glasses refer to the transmission curves shown in Bureau of StaudardsTechnologic paper 148. The letter "W" denotes a Wratten filter, and the numberrefers to the transmission curves found in the booklet, "Wratten Fi l ters ," pub-lished by the Eastman Kodak Company.
*A11 but the last column of this table is taken from Visscher and Luce (1928).
lamp placed at the proper distance (see Table I). A darkperiod of twenty seconds was allowed between exposures. Ineach case, the number of animals in the half of the aquariumtoward the light was counted.
It was found that the animals became more positive tolight after a series of experiments than they had been at thestart. The reaction to the colors, however, was the same,regardless of the order in which they were used. That is, thereaction to a given filter was the same whether it was used atthe beginning or at the end of a set of experiments.
224 HYMAN LUMER Vol. XXXII
III. RESULTS.
In Table II are given the results of several series ofexperiments on Moina brachiata. Tables III, IV, and V giveresults similarly obtained for Leptodora kindtii, Daphnia magna,and Daphnia pulex. These results are shown more graphicallyin Figure 2. It is immediately evident from the curves in this
X
TABLE II.
RESULTS OF EXPERIMENTS TO DETERMINE THE DISTRIBUTION OF STIMULATINGEFFICIENCY AMONG DIFFERENT PORTIONS OF THE SPECTRUM OF EQUAL ENERGY
CONTENT, FOR MONIA BRACHIATA. THE FIGURES GIVEN IN EACH SETOF EXPERIMENTS ARE THE TOTAL NUMBERS OF ANIMALS POSITIVE
TO EACH LIGHT IN THREE EXPOSURES.
Average temp. - 21.0° C.Moina brachiata.
figure that the red end of the spectrum is greater in stimulatingeffect than the blue end. The maximum is in the orange, atabout 640MM for Daphnia pulex and Leptodora kindtii, and atabout 620MM for Daphnia magna. In the case of Moinabrachiata, there are two maxima of equal efficiency, one in thegreen at about 540MM and the other in the orange at about640MM- There is also a secondary maximum in the blue atabout 440jitjU, not very pronounced for Leptodora kindtii, butmore definite for the other forms.
FILTERSAnimalsExperiments perments Experi-
ment
Total....
Percentpositive
Cor-rectedfor Red
No. 3 LIGHT REACTIONS OF CLADOCERA 225-
I t is interesting to note t ha t al though the distribution ofstimulating effect is similar in these forms, there are differencesin the curves for each species. Those for Daphnia pulex andLeptodora kindtii are most alike. T h a t for Daphnia magnadiffers from these in tha t the maximum is slightly different,and t ha t the st imulating effect of green is relatively less. While
Percent of animals positive
SO 30 40 50 60
FIGURE 2. Curves showing the distribution of stimulating efficiency among colorsequal in radiant energy content.
226 HYMAN LUMER Vol. XXXII
the curve for Moina brachiata appears markedly dififerent fromthe others, it may be noted that it is quite similar to that forDaphnia pulex from the violet through the green; after that theeffect is relatively much greater in the latter form.
There is, in the case of Daphnia pulex and Leptodora kindtii,a slight increase in effect toward the ultra-violet, while in the
TABLE III .
RESULTS OF EXPERIMENTS TO DETERMINE THE DISTRIBUTION OF STIMULATING"• EFFICIENCY AMONG DIFFERENT PORTIONS OF THE SPECTRUM OF EQUAL ENERGY
CONTENT, FOR LEPTODORA KINDTII. THE FIGURES GIVEN IN EACH SETOF EXPERIMENTS ARE THE TOTAL NUMBERS OF ANIMALS POSITIVE
TO EACH LIGHT IN THREE EXPOSURES.
Average temp. = 26.0° C.Leptodora kindtii.
Experi-ments
12345.6789..
1011
Total....
Percentpositive
Cor-rectedfor Red
Animalsper
Experi-ment
7animals8 "
10 "8 "
10 "8 «9 "
10 "10 "10 "10 "
100animals
FILTERS
C83
54
11431424
3
43
14.3
13.1
C69
25
101
042443
37
12.3
10.8
W35
34q3
276
44
46
15.3
13.7
W49
56
116
563345
56
18.7
C60
66
11435
135366
59
19.7
C59
648fi46
135366
67
22.3
C56
5
11863
126476
75
25.0
C52
87
1111109
1193
119
92
30.7
W58
99
1?141611151369
12
126
42.0
W15
6131514161214219
1114
145
48.3
W22
10131?18
13171611
18
160
53.3
C38
111410179A151619101415
165
55.0
C19
8171316
1518177
148
155
51.7
other two species, the efficiency is lowest in this region. Itwould have been desirable to test this region further, butthis was not possible with the apparatus used, since light froma tungsten filament does not penetrate far into the ultra-violet.
It is also interesting to observe that the effect of red israther high in three of the species; in fact it is almost as greatas that of orange. For Moina brachiata, on the other hand,it is scarcely higher than the effect of violet.
No. 3 LIGHT REACTIONS OF CLADOCERA 227
IV. DISCUSSION AND CONCLUSIONS.
It is apparent that the results of these experiments differfrom those of previous investigators, first, in that here theefficiency of the orange is greater than that of the green, orat least equal to it (Moina brachiata), and second, in that herethe efficiency of red is relatively high, being, with the exception
TABLE IV.
RESULTS OF EXPERIMENTS TO DETERMINE THE DISTRIBUTION OF STIMULATINGEFFICIENCY AMONG DIFFERENT PORTIONS OF THE SPECTRUM, OF EQUAL ENERGY
CONTENT, FOR DAPHNIA MAGNA. THE FIGURES GIVEN IN EACH SET OFEXPERIMENTS ARE THE TOTAL NUMBERS OF ANIMALS POSITIVE TO
EACH LIGHT IN THREE EXPOSURES.
Average temp. = 21.0° C.Daphnia magna.
Experi-ments
123456789
10
Total....
Percentpositive
Cor-rectedfor Red
Animalsper
Experi-ment
6 animals9 "
14 «8 «7 "
13 "8 "
10 "12 "13 "
100animals
FILTERS
C83
1124727339
39
13.0
11.8
C69
237163
1053
10
50
16.7
15.2
W35
176975
11779
69
23.0
21.4
W49
035566
13128
13
71
23.7
C60
522754966
11
57
19.0
C59
512853
1135
12
55
18.3
C56
2378649279
57
19.0
C52
055854
1114
11
54
18.0
W58
177867
1135
12
67
22.3
W15
46
111386
1886
18
98
32.7
W22
38
16178
1016135
14
110
36.7
C38
65
1017110
1697
14
104
34.7
C19
05 0
50
0
O1
1—11—
1
4139
126
93
31.0
of Moina, higher than that of the green. On the other hand,the results are similar to those obtained by v. Frisch andKupelweiser, Becher, Koehler, and Peters, in that the animalsare, as a rule, more positive to green, yellow, orange, and red,than to blue and violet. The only exception to this is Daphniamagna, which is about equally positive to green and blue.
The explanation of the discrepancies between these resultsand others may lie in one or more of the following factors;physiological condition; age; or the distribution of radiantenergy in the spectrum.
.228 HYMAN LUMER Vol. XXXII
The results in question were obtained with animals positiveto light. The animals used in these experiments were eitherneutral (Daphnia^ pulex, Moina brachiata) or negative {Daphniamagna, Leptodpra kindtii) to white light. Mast (1917) hasshown that for certain organisms the distribution of stimulatingeffect is the same whether the organisms are positive or negative
TABLE V.
RESULTS OF EXPERIMENTS TO DETERMINE THE DISTRIBUTION OF STIMULATINGEFFICIENCY AMONG DIFFERENT PORTIONS OF THE SPECTRUM, OF EQUAL ENERGY
CONTENT, FOR DAPHNIA PULEX. THE FIGURES GIVEN IN EACH SET OFEXPERIMENTS ARE THE TOTAL NUMBERS OF ANIMALS POSITIVE TO
EACH LIGHT IN THREE EXPOSURES.
Daphnia pulex.Average temp. = 21
Experi-ments
123456789
10
Total. . . .Percentpositive
Cor-rectedfor Red
Animalsper
Experi-ment
10 animals10 "10 "10 "10 "10 "10 "10 «9 "6 «
95 animals
5°C
FILTERS
C83
11Ifi121518171814105
136
47.7
46.5
C69
811q
1117121610107
111
38.9
37.4
W35
1?108
12171314191211
128
44.9
43.3
W49
8101?1724231614
• 167
147
51.6
C60
151411152122188q6
139
48.7
C59
131810132022161477
140
49.1
C56
8207
16222113108
10
135
47.4
C52
10201516242320169
12
165
57.9
W58
142299,232418iq1099
170
59.6
W15
172520191922iq141516
186
65.3
W22
20232321242221142316
207
72.6
C38
9426?,?,25231923202214
218
76.5
C19
192323252717iq212612
212
74.4
to light. Although this has not been definitely shown forcladocera, it is rather to be expected, particularly if the distribu-tion of stimulating effect depends on the presence of a fixedphotosensitive substance. Consequently, the factor of physio-logical condition is, to a great extent, ruled out. A series ofexperiments on positively phototropic animals would be re-quired, however, to settle this point definitely.
It is known that the phototropic reactions of cladocerachange with age, Newly hatched animals are positive to lightat all temperatures. As they grow older, however, they become
No. 3 LIGHT REACTIONS OF CLADOCERA 229
neutral or negative to light, and are positive only at low tem-peratures, the range depending on the particular species.This indicates primarily a change in physiological condition,but there is also a possibility that the nature of the photo-sensitive substance may change with age. In previous work,animals in various stages of development were used; here, theanimals used were as nearly as possible of the same age.However, since animals of only one age were used, nothingdefinite can be said here concerning this factor.
It may be noted that in practically all previous investigationswith Daphnia, in which the region of maximum efficiency wasfound to lie in the green or yellow, the monochromatic lightwas produced by a prismatic spectrum. The radiant energy•of a prismatic spectrum increases from the blue to the red,slowly at first, then more rapidly (Mast, 1911, p. 306; 1917,p. 490). Thus, the radiant energy of the orange and redused in such experiments is much greater than that of thegreen and yellow. It is quite probable that the energy of theorange and red was, in cases where a prismatic spectrumwas used, too great to elicit a positive response, especiallysince these animals are positive only within a limited rangeof intensities. With colors equal in energy, however, sucha probability is eliminated; here the response to color is nothidden by an opposite response to intensity. This factor isthe one which most readily explains the discrepancies betweenthe results of these and previous investigations.
It may be concluded, accordingly, that the animals investi-gated are more strongly stimulated by some wave-lengthsthan by others, when the intensity of the various wave-lengthsis equal. There is a region of maximum stimulating efficiencyin the orange (620-640/x/̂ ) for all the species investigated, andalso an equal maximum in the green at about 540/xjLt for Moinabrachiata. The stimulating effect falls off greatly toward theviolet end, with a secondary maximum in the blue at about440/̂ u, and very little toward the red, except in the case ofMoina brachiata. That these reactions are specific effects ofthe wave-lengths involved, and are not due merely, to theamount of ultra-violet transmitted by each filter, as Bechermaintains, is evident from the fact that not only is little ultra-violet transmitted by any but the purple filters, but whateveris transmitted is almost completely absorbed by the threelayers of glass through which the light passes.
230 HYMAN LUMER Vol. X X X I I
A comparison of the curves in Figure 2 warrants the furtherconclusion that the photosensitive substances in these fourspecies, although fundamentally similar, are specific for eachspecies. It is interesting to note that the curve for Daphniapulex is more similar to that for Leptodora kindtii than it isto that for Daphnia magna. This indicates, as do the resultsof Mast (1917) and Hecht, (1928), that distribution of stimulat-ing effect in the spectrum is riot correlated with the degree inwhich the species are related.
V. SUMMARY.
1. Pour species of cladocera {Moina brachiata, Leptodorakindtii, Daphnia pulex, and Daphnia magna) were exposed toa series of thirteen colored lights of equal intensity, and thepercentages of the total number positive to each light de-termined.
2. Orange light (620-640^) was found to have the maxi-mum stimulating effect for all the species investigated. ForMoina brachiata, the efficiency of green light (about 540 /̂i)was approximately equal to that of orange. The discrepancybetween these results and those of previous investigators, whomaintained that green light had the maximum stimulatingefficiency, is most probably due to the fact that colors equalin intensity were used in these experiments.
3. The stimulating efficiency falls off greatly toward theviolet, with a secondary maximum in the blue at about 440JUJU,but very little toward the red, except in the case of Moinabrachiata, where the effect of red is very low.
4. The curves for the distribution of stimulating efficiency,although essentially similar for these forms, are neverthelessdifferent in certain details for each species. This indicatesthat the photosensitive substances are specific for each species,,although fundamentally similar.
5. The similarity of the curves for two species is not cor-related with the degree of relationship of the species since thecurve for Daphnia pulex is more similar to that for Leptodorakindtii than it is to that for Daphnia magna.
BIBLIOGRAPHY.Banta, A. M. "A Convenient Culture Medium for Daphnids." Science, N. S..
Vol. 53, 1921, pp. 557-558.Becher, S. "Neue Versuche zum Problem des Licht- und Parbensehens der
Daphnien." Verh. D. Zool. Ges., Bd. 26, 1921, s. 60-67.
No. 3 LIGHT REACTIONS OF CLADOCERA 231
Bert, P. "Stir la question de savoir si toux les animaux voient les memes rayonsque nous." Arch, de Physiol. T. 2, 1869, p. 547.
Borowski, V. "Uber das Verhalten von Daphnia pulex im verschiedenfarbigenLichte." Rusk, fisiologicesk. Zurnal. Bd. 10, 1927, s. 11-31.
Ewald, W. F. "Versuche zur Analyse der Licht- und Farbenreaktion eines Wir-bellosen (D. pulex)." Zeitschr. fur Sinnes Physiol. Bd. 48, 1914, s. 285-324.
Gardner, K. S., Tyndell, E. P. T., and McNichols, H. J. "The Ultra-violet andVisible Transmission of Various Colored Glasses." Technologic Papers of theBureau of Standards. No. 148, 27 pp. Washington, 1920.
Hecht, Selig. "The Relation of Time, Intensity, and Wave-length in the Photo-sensory System of Pholas." Journ. Gen. Physiol., Vol. 11, 1928, pp. 657-672.
Hess, C. "Neue Untersuchungen uber den Lichtsinn bei wirbellosen Tieren."Arch.f. d. ges. Physiol.. Bd. 136, 1910, s. 282-367.
Klugh, A. Brooker. "The Ecology, Food-relations, and Culture of Fresh-waterEntomostraca. Transact. Roy. Canad. Inst., Vol. 16, 1927, pp. 15-98.
Loeb, Jaques, and Maxwell, S. S. "Further Proof of the Identity of Heliotropismin Animals and Plants." Univ. of Cal. Pub. Physiol., Vol. 3, 1910.
Lubbock, Sir J. "On the Sense of Color among Some of the Lower Animals.Part. I." Journ. Linn. Soc. (Zool.), Vol. 16, 1881, pp. 121-127.
Mast, Samuel O. Light and the Behavior of Organisms. New York, John Wileyand Sons, 1911, 410 pp.
Mast, Samuel O. "The Relation between Spectral Color and Stimulation in theLower Organisms." Journ. Exp. Zool., Vol. 22, 1917, pp. 471-528.
Peters, Ernst. "Vergleichende Untersuchungen uber den Lichtsinn einheimischerCladocerenarten." Zool. Jahrb. allg. Zool., Bd. 43, 1926, s. 1-40.
Visscher, J. Paul, and Robert H. Luce. "Reactions of the Cyprid Larvae ofBarnacles to Light with Special Reference to Spectral Colors." Biol. Bull.,Vol. 54, 1928, pp. 336-350.
v. Frisch, K., und H. Kupelweiser. Uber den Einfluss der Lichtfarbe auf diephototaktischen Reaktionen neiderer Krebse." Biol. Cent., Bd. 33, 1913,s. 517-552.
Yerkes, R. M. "Reactions of Entomostraca to Stimulation by Light." Amer.Journ. Physiol., Vol. 3, 1899, pp. 157-182.
The Emergence of Life.This book is an attempt to interpret Emergent Evolution on the basis of logical
and mathematical theories which have been prominent in recent scientific dis-cussion; and also to gather up suggestions from the classic philosophers. Thebasic interpretation is an idealistic theory of reality. The monadology of Leibnizis given a central position, though reinterpreted in a manner deemed necessaryin the light of later thought. The emergence of life is regarded as followinglines capable of accurate description in terms of mathematical logic. This callsfor a reduction of structure to infinitesimals of the infinite order, and for a dis-crission of continuity and discontinuity in the light of mathematical-logical analysisof these concepts. Contributions are drawn from a wide range of scientific liter-ature, physical and biological.
The result is an imposing array at certain points of mathematical and logicalformulae, though their connection with the thesis presented is often so brieflygiven that the necessity of the connection and relevance to the theory are notclearly evident. The massing of differential equations, radicals, vector analyses,theory of groups, etc., seems more like a display of elaborate erudition than aconvincing straightforward argument. To the general reader it looks quiteforbidding. To the specialist it might easily look over-ambitious. An effectivesynthesis in a single volume might well dwell longer upon fundamental principles,rather than attempt to present too much detail, fundamental as this is ultimately.
—A. E. AVEY.
The Emergence of life, by J. B. BURKE, viii+396 pp. Oxford Univ. Press,1931. $7.50.
