Embryonic Growth in Animals 217 



related to vitamin B^o, or folic acid, deficiency. A dose of 0.015 mg. 

 of colchicine in saline solution ^vas found to arrest all mitoses in the 

 voung chick embryo. The number of mitoses found after four and 

 eight hours was counted. This gives a precise idea of the proliferative 

 activity of these cells. In chicks at the sixtieth hour of growth, eight 

 liours after colchicine, the number of megaloblastic mitoses is in- 

 creased more than tenfold; while in controls. 38.6 cells per thousand 

 are in division; in treated chicks, eight hours after colchicine, the fig- 

 ure reaches 457.9. This increase is markedly greater than that found in 

 the bone marrow of Biermer anemia patients. However, the technique 

 being different, the comparison is not quite valid. What is more in- 

 teresting from the viewpoint of embryological growth, is that the 

 mcgaloblasts are demonstrated to divide more than the undiffer- 

 entiated connective cells from which they originate. 



A detailed study of the relation between differentiation of the 

 red blood cells and cell division in the chick embryo at different 

 stages of growth has clearly indicated a decrease in mitotic activity as 

 soon as hemoglobin is synthesized. Colchicine has been a remarkable 

 tool for the precise study of this problem. ^ No doubt, it will not be 

 the last contribution in a field open to many types of investigation 

 (cf. Chapter 9) . 



REFERENCES 



1. Ancel, p. Sur la mise en evidence de differences individuelles dans la consti- 

 tution des enil)ivons par Taction associce de deux substances chimiques tera- 

 togenes. C. R. Soc. Biol. Paris. lll:20S-9. 1947. La Chimioteratogenese. 

 Realisation des monstruosites par des substances chimiciues chez les verte- 

 bres. G. Doin et Cie., Edit., Paris. 19.59. 



2. , AND Lallemand, S. Sur la teratogcnie de la strophosomie experi- 



mentale chez le poulet. C. R. Soc. Biol. Paris. 130:385-87. 1939. Sur le diag- 

 nostic precoce de la strophosomie dorigine colchicini([ue chez lenibrxon de 

 poulet. C. R. Soc. Biol. Paris. 130:139(M)9. 1939. Sur la realisation aumoyen 

 de la colchnicine d'embryons de poulets coelosomiens. C. R. Soc. Biol. Paris. 

 130:1399-1401. 1939. Sur la realisation experimentale de la coelosomie par 

 divers mecanismes. C. R. Soc. Biol. Paris. 137:3-4. 1944. 



3. .\STALDI, G., Bernardelli, E., and Rondanelli. E. La colchicine dans letude 

 de la proliferation des cellules hcmopoictic|ues de Tembryon. Rc\ . Beige Path. 

 21:406-13. 1952. Studv on the proliferation of embrvonic ervthroblasts. Rev. 

 Beige Path. 22:172-78; 1952. 



4. Beams, H. W., and Evans, T. C. Some effects of colchicine upon the fust cleav- 

 age in Jrbflr/a /)(/»f/!//r;/rt. Biol. Bull. 79:188-98. 1940. 



.5. Bretscher, .\. Reduktion der Zehenzahl bei Xenopus-I ar\en nacli lokalei 

 Colchicin-behandlung. Rev. Suisse Zool. 54:273-79. 1947. 



6. Brock, N., Drickrey, H.. and Herken. H. Uber Kerngiftc luul Cxtoplasma- 

 gifte, .Arch. Exp. Path. Pharm. 193:679-87. 1939. 



7. BcsHNELL, R. J. Some effects of colchicine on the early development of the 

 frog. Ratia pipiens. .\nat. Rec. 72:Suppl. p. 97. 1938. 



8. Chang, M. C. Artificial production of monstruosities in the rabhii. Nature. 

 154:150. 1944. 



9. CoEOMBO, G. L'azione della colchicina sulla sviluppo embrionalc di Rana 

 agilis. Boll. Soc. Ital. Biol. Sper. 20:657-58. 1945. 



10. Gabriel, M. L. Production of strophosomy in the chick embr\o l)\ local 

 applications of colchicine. Jour. Exp. Zool. 101:35. 1946. The effect of local 



