JOURNAL OF MICROSCOPICAL SCIENCE. 



EXPLANATION OF PLATES XXII, XXIII & XXIV, 



Illustrating Mr. T. Iwakawa's Paper on " The Genesis of 

 the Egg in Triton.^' 



In all these plates the same letters have been employed to mark corre- 

 sponding parts. 



b. Blood-corpuscle. ,/. ep. Follicular epithelium, g. ep, Germinal epi- 

 thelium, g. c. Germ-cell. g. 71. Nucleus of the germ-cell. g. sp. Ger- 

 minal spots. g. V. Germinal vesicle. /. e/;. Lining epithelium. I. n. 

 Nucleus of the lining epithelium, n. Nucleus of the germinal epithelium. 

 p. 0. Primordial ovum. sL Stroma. st. n. Nucleus of the stroma. 

 V. m. Vitelline membrane, y. Yolk-spherules, y, p. Yolk-patches. 



All figures were outlined by the aid of the camera lucida. 



PLATE XXII. 



Fig. 1. — A small piece of the ovary of an adult Triton, treated with 

 argentic nitrate, seen from the external surface. The three strata — 

 germinal epithelium {g. ep), stroma {st.), and lining epithelium {I. ep.) — are 

 distinguished by the size and colour of their nuclei — brown, yellow, and 

 pink, respectively. Two germ-cells (g. c.) are seen still within the mother- 

 cell. X 450. 



Fig. 2. — A portion of the germinal epithelium, showing a nucleus in pro- 

 cess of division, x 450. 



Fig. 3. — A portion of the same, showing the two nuclei some time after 

 the division. The nucleus of the germ-cell is granular, x 450. 



Fig. 4 represents a germ-cell with two nuclei still within the mother- 

 cell, which is surrounded by six epithelial cells, the nuclei of which lie in 

 close proximity with the central mother-cell, x 450. 



Fig. 5. — A similar case, in which the germ-cell has but one nucleus, as 

 is usually the case at this stage, x 450. 



Fig. 6. — The germ-cell {g. c.) begins to project beyond the limits of the 

 mother-cell, under the adjacent epithelial cells, x 450. 



Fig. 7. — A single mother-cell, treated with acetic acid. The nucleus («.) 

 has a peculiar form, never seen in non-proliferating cells. The expansion 

 of the germ- cell has probably caused it to become concave on the side of 

 contact. X 450. 



Fig. 8. — A young ovum, with germinal vesicle and yolk concrement. 

 X 165. 



Fig. 9. — An ovum, surrounded with nuclei of the germinal epithelial 

 cells and five germ-cells, in two of which the nuclei are in process of 

 division. Treated with Kleinenburg's fluid. Cell limits not seen, x 165, 



