MODIFICATION OF DEVELOPMENT IN THE FROG 49] 
(c) 5 hours in LiCl, plus 77 hours in water. Generally no 
advance—dead or dying as equatorial gastrulae. 
-Lot E. (a) 18 hours in LiCl, plus 34 1/2 hours in water. No ad- 
vance over Lot A (a). 
Experiment IV 59. Eggs from the same batch and of the same age 
as those used in experiment IV 58 were placed in m/10 LiCl. Eggs 
removed to water at intervals of 1 1/2, 3, 5, 24, and 53 1/2 hours. 
Lot A. (a) 18 hours in LiCl. Late, inhibited gastrulae to early 
yolk plug stages. 
(b) 53 hours in LiCl. Early neural fold stages, most of 
which have a long narrow yolk plug—a consequence of the relatively 
greater inhibition of the dorsal lip region. Figure 1, dorsal and 2, 
lateral views of a single embryo, shows an oblong yolk plug extending 
over approximately 90°. Figures 52, 53 show in outline two views of 
the same embryo 16 1/2 hours later. The embryo is microcephalic, 
ventral suckers approximated but not entirely ‘fused’ and with the 
neural groove open through most of its length. Figures 54, 55 show 
two similar embryos from the same lot. 
(c) 93 hours in LiCl. All degrees of approximation to com- 
plete ‘fusion’ of ventral suckers and olfactory pits. All of the embryos 
have permanent yolk plugs. Many are nearly or quite anencephalic. 
Others show the anterior part of the neural groove open and undergoing 
disintegration (figs. 3, 4, 5, 6). 
(d) 107 hours n LiCl. No further advance. Almost all 
dead. 
Lots B, C, D. Eggs exposed 1 1/2, 3 and 5 hours to this solution 
and then returned to water, hatched s'multaneously or slightly behind 
the control, showing no marked effects of the treatment. 
Lot E. (a) 24 hours in LiCl, plus 28 1/2 hours in water. Some 
differential inhibition as shown by the relatively greater retardation of 
the dorsal lip region. Neural folds just closing. A small yolk plug 
is still present. 
(b) 24 hours in LiCl, plus 57 1/2 hours in water. Hatching 
slightly behind the control. Almost complete recovery. Tails seem 
relatively a little larger than in control. 
Lot F. (a) 53 1/2 hours in LiCl, plus 28 hours in water. Marked 
differential inhibition. The embryos show all degrees of approximation 
to complete ‘fusion’ of ventral suckers and olfactory pits. 
(b) 53 1/2 hours in LiCl, plus 114 hours in water. Micro- 
cephalic embryos with ventral suckers, olfactory pits, and optic vesicle 
approximated or ‘fused.’ All of the embryos show varying degrees of 
differential recovery as indicated by the dorsal convexity and dispro- 
portionately large tails. Figures 56 to 60 show five of the embryos 
after 10 days in water. 
