Pr.ATE LXXI. 



1 57-163. Various stages of cleavage of the egg of the trout, a. Germ. b. Section of yolk on which 

 the germ lias. p. nS. (These figures sire referred to in the text, by error, as 146-150.) 



FIG. 164. Germ in an early stage of cleavage, seen in profile. 

 a. Vitelline membrane. 6. Germ. c. Yolk. 



Fio. 165. Vertical section of blastoderm of the egg of a trout 

 at the third day. a. Germ, already split into a large number of 

 elements, in some of which the dark yolk granules can be dis- 

 tinctly recognized. ; Yolk of the saucer-shaped depression, filled 

 with fat globules. 



FIG. 166. Similar preiwrution, made at the sixth day. The blastoderm, which lies on the yolk like a cushion, 

 consists, as in the previous figure, of small, distinctly nucleated elements. The deein-r element*, those not so 

 far advaiiced in cleftTBge, ;uv larger, and still contain yolk granules. 



