142 TEMPERATURE AND EMBRYONIC DEVELOPMENT 



2. Eggs exposed to extremes of temperature prior to the first cleavage are likely to 

 show numerous abnormalities, and may {Witschi, 1930) even show some imbalance 

 of the sex ratio if carried to the time of sex identification (i. e. , metamorphosis). 



3. Subjection of the pre-gastrula embryos to extremes of temperature change is apt to 

 interfere with the normal progress of gastrulation and may produce spina-bifida and 

 other manifestations of interference with the "organizer" activity of the dorsal lip of 

 the blastopore. 



It seems possible to expand the normal temperature range by artificial means (Lillie and 

 Knowlton, 1896). Eggs of any species, reared at low normal temperatures, will tolerate 

 the sub-normal temperatures better than other eggs reared at higher, but normal tem- 

 peratures. The range of Bufo lentiginosus was increased by as much as 3. 5°C. by such 

 acclimatization (Davenport and Castle, 1896). DuShane and Hutchinson (1941) have demon- 

 strated that the development of form and the development of behavior are differentially 

 affected by temperature differences. 



REFERENCES 



ATLAS, M. , 1935 - "The effect of temperature on the development of Rana pipiens. " Physiol. Zool. 8:290. 



BELEHRADEK, ]., 193S - "Temperature and living matter." Protoplasma Monograph 8. 



BUCHANAN, ]. W. , 1940 - "Developmental rate and alternating temperatures. " Jour. Exp. Zool. 83:235. 



CONKLIN. E. G. , 1938 - "Disorientations of development in Crepidula plana produced by low temperatures. " Proc. Am. Phil- 

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CROZIER, W. J., 1926 - "On curves of growth especially in relation to temperature. " Jour. Gen. Physiol. 10:53. 



DAVENPORT, C. B. G W. E. CASTLE, 1896 - "Studies in morphogenesis. III. On the acclimatization of organisms to high tem- 

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DuSHANE, G. P. G C. HUTCHINSON, 1941 - "The effect of temperature on the development of form and behavior in amphibian 

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HOADLEY, L. , 1938 - "The effect of supra-maximum temperature on the development of Rana pipiens. " Growth. 2:25. 



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KROGH, A., 1914 - "On the influence of temperature on the rate of embryonic development." Zeit. f. Allg. Physiol. 16:163. 



LILLIE, F R. G F. P. KNOWLTON, 1898 - "On the effect of temperature on the development of animals. " Zool. Bull. 1:179. 



MOORE, J A., 1939 - "Temperature tolerance and rates of development of eggs of Amphibia. " Ecology. 20:459. 



MOORE, J. A. , 1940 - "Adaptive differences in the egg membranes of frogs. " Am. Nat. 74:89. 



MOORE, J. A., 1942 - "The role of temperature in speciation of frogs. " Biol. Symp. 6:189. 



MOORE, J. A. , 1942 - "Embryonic temperature tolerance and rate of development in Rana catesbiana. " Biol. Bull. 83:375. 



MOORE, J. A. , 1949 - "Patterns of evolution of the genus Rana. " in "Genetics, Paleontology, and Evolution. " Jepson et al (eds) 

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OLSON, J. B. , 1942 - "Changes in body proportions produced in frog embryos by supra-normal temperatures. " Proc. Soc. Exp. 

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POLLISTER, A W. G J. A. MOORE, 1937 - "Tables for the normal development of Rana sylvotica. " Anot. Rec. 16:144. 



RYAN, F. J., 1941 - "The time-temperature relation of different stages of development. " Biol. Bull. 81:432. 



RYAN, F. J., 1941 - "Temperature change and the subsequent rate of development. " Jour. Exp. Zool. 88:25. 



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"No concrete argumenl can be advanced to separate form and function in 

 their essence. " Dalcq 



"Nature is never more perfect than in small thuigs. " Pliny 



