PLATE II. 



Fig. 14. Optical section of an old blastula. (From life.) J Ob. X 8 Oc. Camera. X 360. 



Fig. 11". Section through an old blastula showing endodermal bodies in blastoccele. fa Oil Immersion. X 8 Or. 



Camera. ; 704. 

 Fig. 15. Longitudinal section through older blastula than that of fig. 14k Bhowing proliferation of endoderm cells. 



r V Oil Immersion. 8 0c. Camera. X 704. 

 Fig. 15a. Transverse section through a gastrula which is just beginning to gastrulate. Taken through ganglionic 



thickening, fa Oil Immersion. X 8 Oc. Camera. X 704. 

 Fig. L56. Transverse- section through same specimen as that of fig. L5a. Taken through the middle of the gastrula. 



[', ( )il Immersion. X 8 Oc. Camera. X 704. 

 Fig. 16. Longitudinal section through a gastrula which has begun to elongate. -,', Oil Immersion. >. s Oc. 



Camera. X 704. 

 Fig. 16a. Transverse section through anterior end of a gastrula which was a little younger than that of fig. 16. 



Taken just back of the ganglion. fa Oil Immersion. X 8 Oc. Camera. 704. 

 Fig. 166. Transverse section through same specimen as that of fig. 16a. Taken just in front of anterior end of the 



archenteron. Shows mesoderm arising from the latter. jV Oil Immersion. X 8 Oc. Camera. X 704. 



Fig. 1 tic. Continuation of above series. Taken through anterior part of archenteron. fa Oil Immersion. X8 



Oc. Camera. X 704. 

 Fig. 10'/. Continuation of above series. Taken through middle of archenteron. T V Oil Immersion. X 8 Oc. 



Camera. X 704. 

 Fig. 16e. Continuation of above series. Taken through posterior part of archenteron. fa Oil Immersion. 



X8 0c. Camera. X 704. 

 Fig. 16/.- Continuation of above series. Taken through the region where the lips of the blastopore are closing up. 



i iil Immersion. 8 0c. Camera. X 704. 

 Fig. Hi;;. Horizontal section through a gastrula of the same age as that of liu'. 16. ,'. < >il Immersion. s Oc. 



Camera. X 704. 

 Fig. 17. Transverse section through a gastrula showing peculiar granular cells arising from the endoderm. rV Oil 



Immersion. X 8 Oc. Camera. X 704. 

 118 



