Figs.1 to9 Differential inhibition forms. 1, lateral; 2, dorsal view of one 
embryo. Eggs in late cleavage stages when placed in the solution. Treatment: 
53 hours in m/10 LiCl. Note the elongated yolk plug which appears to result 
primarily from the relatively greater retardation of the dorsal lip region. Two 
outline views of the same embryo made sixteen and one-half hours later are 
shown in figures 52,53. 3, same as above, but after 93 hours in m/10 LiCl. Ven- 
tral suckers, v.s., are ‘fused.’ 4, 5, 6, three embryos from same lot as the one 
shown in 3. 7, lateral, 8, dorsal view of one embryo, and 9, lateral view of a 
second embryo. Eggs unsegmented when placed in the solution. Treatment: 
76 hours in m/10.62 LiCl + 20 hours in water. 6, open brain region; y.p., yolk 
plug; v.s., ventral sucker. The anterior end is toward the top of the page in all 
figures, save 3. Figures 1 to 6, from Exp. IV 59; 7 to 9, from Exp. IV 22; 4, 5, 6, 
drawn to slightly smaller scale. 
478 
a 
