160 SEPARATION OF GROWTH AND DIFFERENTIATION 



into a relatively fluid agar medium. Such uniform restriction does not impede the forma- 

 tion of neural folds, or of other invaginations such as the stomodeum, proctodeum, ol- 

 factory pits, etc. The total volume of the egg (or embryo) remains almost static. The 

 evaginations, such as the optic vesicles, gills, balancers, and limb-buds are apt to be 

 restricted. Intra-cellular imbibition are limited and concern particularly the mesen- 

 chyme. It is not yet known whether mitosis is in any way inhibited, but certainly mor- 

 phogenetic movements are not. While the general shape and size (growth factors) of the 

 embryo remains much as they were at the time of embedding, there is not present a 

 parallel restriction of differentiation. 



REFERENCES 



ADOLPH, E. F. , 1931 - "Body size as a factor in the metamorphosis of tadpoles. " Biol. Bull. 61:376. 



BARNES M. R. , 1944 - "The metabolism of the developing Rana pipiens as revealed by specific inhibitors. " Jour. Exp. Zool. 



95:399. 

 BRAGG, A N , 1938 - "The organization of the early embryo of Bufo cognatus as revealed especially by the mitotic index. " 



Z. Zelif. mirk. Anat. Berlin. 28:154 (see also 1939; Bio. Bull. 77:268). 

 BRIGGS, R. , 1946 - "Effects of the growth inhibitor, hexenolactone, on frog, embryos." Growth. 10:45. 

 BRIGGS. J. B. G R. W. BRIGGS, 1943 - "The effects of water-soluble carcinogen on early frog development. " Cancer Research. 



3:1. 

 BROWN, L. A., 1927 - "On the nature of the equation for growth processes, " Jour. Gen. Physiol. 11:37. 

 BROWN. M. G. G V. HAMBURGER, 1941 - "Density studies on amphibian embryos with special reference to the mechanism of 



organizer action. " Jour. Exp. Zool. 88:353. 

 BUCHANAN, J. W. , 1938 - "Differential acceleration following inhibition. " Jour. Exp. Zool. 79:11 1 (see ibid, 1940: vol. 



83:235). 

 BURT, A. S. , 1943 - "Neurulation in mechanically and chemically inhibited Amblystoma. " Biol. Bull. 85:103. 

 COPENHAVER, W. M. & S. R. DETWILER, 1941 - "Developmental behavior of Amblystoma eggs subjected to indolebutyric acid. " 



Anat. Rec. 79:247. 

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

 DALCQ, A. G J. PASTEELS, 1937 - "Une conception nouvelle des bases physiologiques de la morphogenese. " Arch, de Biol. 



48:669. 

 DAWSON, A. B. , 1938 - "Effects of 2, 4-dinitrophenol on the early development of the frog. Rana pipiens. " Jour. Exp. Zool. 78. 

 DEMPSTER, W J. , 1933 - "Growth in Amblystoma punctatum during the embryonic and early larval period. " Jour. Exp. Zool. 



64:495. 

 DENT, J. N. , 1942 - "The embryonic development of Plethodon cinereus as correlated with the differentiation and functioning of 



the thyroid gland. " Jour. Morph. 71:577. 

 EAKIN, R. M. , 1939 - "Further studies in regiUatory development of Triturus torosus. " Univ. Calif. Pub. Zool. 43:185. 

 GILCHRIST, F. G., 1928 - "The time relations of determinations in early amphibian development. " Jour. Exp. Zool. 66:15. 

 HAMILTON, W. J. , 1934 - "The rate of growth of the toad Bufo americanus under natural conditions. " Copeia. p. 88. 

 HAMMETT, F S. , 1946 - "What is growth?" Scientia April -June, 1946. 

 HOLTFRETER, J., 1945 - "Differential inhibition of growth and differentiation by mechanical and chemical means." Anat. Rec, 



93:59. 

 HUTCHINSON, C, 1939 - "Some experimental conditions modifying the growth of amphibian larvae. " Jour. Exp. Zool. 82. 

 NEEDHAM, J., 1937 - "On the dissociability of the fundamental processes in ontogenesis. " Biol. Rev. 8:180. 

 PATCH, E. M. , 1927 - "Biometric studies upon development and growth in Amblystoma punctatum and tigrinum. " Proc. Soc. 



Exp. Biol. G Med. 25. 

 PIKE, F. H. , 1923 - "The effect of the environment in the production of malformations. " Ecology. 4:420. 

 RANEY, S. C. G W. M. Ingvar, 1941 - "Growth of tagged frogs (R. catesbiana and R. clamitans) under naturol conditions. " Am. 



Midland Nat. 26:20. 

 REIMAN, S. P., 1947 - "Growth." Ann. Rev. Physiol. 9:1. 

 ROBB, R. C. , 1929 - "On the nature of hereditary size limitations. II. The growth of parts in relation to the whole. " Br. Jour. 



Exp. Biol. 6:311, 

 SHAW, G. , 1932 - "The effect of biologically conditioned water upon the growth in fishes and amphibia. " Ecology. 13:263. 

 STOCKARD, C. R. , 1921 - "Developmental rate and structural expression. " Am. Jour. Anat. 28:115. 

 THOMPSON, D. A. W. , 1917 - "Growth and Form. " Cambridge Univ. Press. 

 TWITTY, V. C. , 1942 - "The role of genetic differentiation in the embryonic development of Amphibia. " Biol. Symposium. 



6:291. 

 TYLER, A , 1947 - "An auto-antlbody concept of cell structure, growth, and differentiation. " Growth Symposium. 7-19. 

 WEISS, P., 1940 - "The problem of cell individuality In development." Am. Nat. 64:34. 



