l8o ' Charles R. Stockard 



in LiNOg ^ m a few show the blastoderm as a polar ball with large 

 bubble-like segmentation cavity (Fig. 5). Many eggs, however, 

 have polar caps with peripheral germ-rings and a small embryonic 

 shield just beginning to form (Fig. 6). A very few are more 

 nearly normal with the germ-ring extending one-third over the yolk 

 sphere. This is the same condition found in eggs of this age in 

 solutions of LiCl, which gives for the first few hours no evident 

 effect, then retards the development, preventing the downgrowth of 

 the germ-ring, and often causing the formation of polar proto- 

 plasmic balls with the bubbles beneath, shown in Figs, i, 2, 3 and 4 

 in my earlier paper ('06). It might be objected that at this stage 

 of development there are only a limited number of ways that the 

 eggs could be afferted. This may be granted, but from what is 

 recorded in other sections of this article it will be seen that there 

 are several possible modifications that may appear, and no other 

 substances have given, with any degree of constancy, the above 

 modifications. Those in the tV m LiNOg solutions were in a simi- 

 lar condition. 



After twenty-three hours in I.ijSO^ yV m .most of the eggs 

 are dead with polar balls of protoplasm. Of those still alive, most 

 have polar caps with bubbles beneath (Fig. 7). Others have 

 polar caps with peripheral germ rings and embryonic shields just 

 forming (Fig. 8); a very few are more nearly normal and show the 

 germ-ring one- fourth the way down the yolk. LioSO^ 5V m haS 

 caused similar though less pronounced effects. 



The control eggs when forty-six hours old show the embryos 

 distinctly marked out with optic vesicles and lenses visible. In 

 the LiNOg i m at this time a few eggs are dead with polar caps; 

 their blastoderms showing a bubble-like appearance beneath. 

 Many have embryonic thickenings forming in the polar caps simi- 

 lar to the condition shown in my former Fig. 18. A few have 

 their caps extending halfway over the yolk with short embryos 

 formed, a few others have the blastopores almost closed although 

 the head end of the embryo is abnormal. In LiNOg yV ni many 

 eggs are dead, a few have their blastopores closed though the head 

 end of the embryo is abnormal with no eyes showing. There are 

 others with the blastoderms only one-half over the yolk and form- 



