592 KEPORT OF COMMISSIONER OF FIHU AND FISHERIES. [li3C] 



EXPLANATION OF PLATE VIII. 



Fig. o3. Tiaosverse optical diagraniiiiatic Bcction tbrough the region of the fin-folds 

 of an embryo cod eighteeen days after impregnation, showing the relation 

 of the spinalThord ms to the chorda dorsalis c/iand the intestine ;, vrith 

 the muscle ])lates pv and segmental ducts sd on either side, x 55. 



Fig. -i'-i (I. (Jerminal disk of cod's egg divided into four segments, and showing dislo- 

 cation of the second cleavage furrow, x 32. 



) IG. 'S.'j h. Germinal disk of shad's egg of two hours, divided like the preceding, 

 and with the second and third cleavage furrows dislocated, x 18. 



Fig. 34. Jlmbryo cod nineteen days after impregnation. The liver, heart, tail, fin- 

 fold, brain, and intestine have made important ])rogress. The heart now 

 i)ulsates regularly, but there are as yet no blood cor])U8cle8, The eye is 

 beginning to develop an outer layer of.pigment, the lamina fusca. The 

 muscle segments or plates have become more numerous. At the upper 

 right-hand side a bell-animalcule, some monads, and an ;ilga are ^bown 

 attached to the vitelline uieuibrane. x 5^.. 



