THE AMPHIBIAN GERMINAL VESICLE 



177 



current, in order to detect these changes in pH. (It is important that after each 

 experiment the copper electrodes be thoroughly cleaned with cotton and acid al- 

 cohol, followed by distilled water, since they will corrode. ) 



c. Combined Acid and Electric Current" Use the set-up as in b. above but before 

 passing the current through the solution containing the germinal vesicle, add to 

 the N-medium, at a point opposite yourself, a small drop of 0. OOlN-HCl. This 

 will bring in the hydrogen ion effect at right angles to the direction of the current. 

 As the 1. E. P. passes over the germinal vesicle, apply the current in short 

 shocks. A continuous current will produce an irreversible coagulum. Movement 

 inside the vesicle will be oriented within the imposed electrical field. 



Fertilization of the human ovum. Note extruded polar 

 body and unsuccessful surrounding spermatozoa. (Courtesy 

 Dr. L. B. Shettles, from "Ovum Humanum", Hafner, Pub. 

 N.Y.) 



Human ovum showing two extruded polar bodies and two 

 pronuclei, one from the ovum and the other from the pen- 

 etrated spermatozoan. From "Ovum Humanum", Dr. L. B. 

 Shettles courtesy. (Pub. Hafner, N.Y.) 



REFERENCES 



BRACHET, J., 1939 - "Quelques proprieties chimiques de la vesicule germinative isolee. " Arch. f. exper. Zellforsch. 22:541. 

 BRIGGS, R. , T. C. KING - "Factors affecting the transplantability of the nuclei of frog embryonic cells. Jour. Exp. Zool. 



122:485. 

 DURYEE, W. R., 1938 - "A microdissection study of amphibian chromosomes. " Biol. Bull. 75:345. 



DURYEE, W. R., 1949 - "The nature of radiation injury to Amphibian cell nucleus. " Jour. Not. Cancer Inst. 10:735-793. 

 LA COUR, L. , 1941 - "Aceto-orcein: a new stain-fixative for chromosomes. " Stain Techno. 16:169. 

 MOORE, B. , 1957 - "Chromosomal vesicles and double nuclei in amphibian embryos. " Jour. Morph. 101:209-223. 

 NEBEL, B. R. , 1939 - "Chromosome structure. " Bot. Rev. 5:563. 

 OGUMA, K. & S. MAKINO, 1937 - "A new list of the chromosome numbers in Vertebrata. " Jour. Fac. Sci. Hokkaido Imp. Univ. 



Japan. 5:297. 

 SAMBUICHI, H. , 1957 - "The roles of the nucleus and the cytoplasm in development. " Jour. Sci. Hiroshima Univ. Ser. B. , 



17:33-46. 

 SHETTLES, L. , 1960 - "Ovum Huminum". Hafner Pub. Co., New York City. 79 pages. 

 STRAUB, J., 1943 - "Chromosomenstructur. " Naturwiss. 31:97. 

 WADDINGTON, G H. , 1939 - "The physico-chemical structure of the chromosomes and the gene. " Am. Nat. 73:300. 



