480 A. W. BELLAMY 
22 
P-yp 25 
Figs. 10 to26 Differential inhibition forms. 10, lateral and, 11, dorsal view 
of one embryo. Eggs in two-cell stage when placed in the solution. Treatment: 
4 days in KNC + 2 days in water. 12, 13, dorsal views of two embryos. Eggs 
four to eight-cell stages when placed in the solution. Treatment: 48 hours 
in 0.0075 per cent formaldehyde. 14, ventral view of an embryo from the same 
lot as 12, 13, but after 72 hours in 0.0075 per cent formaldehyde. This figure 
illustrates a typical spina bifida condition with the two tails projecting dorsally 
from cither side of the yolk plug. 15 to 21, eggs early gastrula stages when 
us 
