PLATE 17 
EXPLANATION OF FIGURES 
The formation of entoderm (concluded). 
1 The 7th section longitudinally through ovum No. 144’ (1); ENT!, dividing 
entoderm mother cell; 16 sections in series; overfixed in Carnoy. X 200. 
2 The 14th section longitudinally through ovum No. 144’ (8); 19 sections in 
series; Carnoy. X 200. 
3 Section taken tangentially through embryonic area of ovum No. 144’ (10); 
14th section (total 19); Carnoy. X 200. 
4 and 5 Sections 9 and 11 (total 25) cut longitudinally through blastocyst 
No. 356 (11); Hill’s fluid; 5 4; ENT’, primitive entoderm cell tending to flat- 
ten out; HNT,? row of entoderm mother cells similar to those in fig. 3, pl. 6. 
x 200. ’ 
6 and 7 Details of ovum No. 356 (4) shown in fig. 12, pl. 18. Fig. 6, 10th 
section (total 25), X 200; fig. 7, 16th section, X 500, with spermatozoa in albumen 
layer; mitosis In embryonic entectoderm; Bouin; 6 ; 283 cells: 
Embryonic ent-ectoderm...5.......5..4:.605.:- 101 cells, in mitosis 3 
simoploplasiChechod erie: sneer nee rene 140 cells, in mitosis 8 
LBA R(oxo Kone age Aerts ck ret ae ere I Re te Sree Sons hata. 42 cells, in mitosis 2 
S8and9 Portions of sections 10 and 17 (total 29) longitudinally through ovum 
No. 356 (9), shown whole in fig. 1, pl. 6; Flemming; 5 yp. X 500. 
10 and 11 Sections 18 and 13, respectively (total 21), longitudinally through 
ovum No. 356 (5), section 12 of which is shown in fig. 3, pl. 9; mitoses in ent- 
ectoderm; Bouin; 6 w; 249 cells: 
Limibynonickent=ectodermesss:.) seen ee eee 75 cells, in mitosis 14 
Trophoblastic’ectoderm. ......¢. ....... osc. see aso. 126 cells; an! mitasiaen 
) Baal oY Kenta eee ren reh in ota ears Cm eae, Pemaans Soar: 48 cells, in mitosis 4 
12 Longitudinal section of egg No. 349 (2) like the one shown in living 
stage is fig. 3, pl. 8; 31st section through vesicle (total 48); 16th section through 
embryonic area (total 28); Bouin;5u. X 200. 
13. Longitudinal section through ovum No. 194’ (4); 7th section through 
embryonic area, (total 20); Hill’s fluid; 74. X 200. 
14. The 9th of a total of 13 sections through the embryonic area of ovum 
No. 194’ (8). X 500. 
15 The 12th of a total of 20 sections through the embryonic area of blastocyst 
No. 194’ (6); 38 sections through vesicle; 74. X 500. 
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