704 RALPH S. LILLIE 
2. Eggs left in sea-water 5 minutes; thence to hypertonic sea-water for 30 minutes; 
returned to sea-water. A large proportion (ca. 50 peu cent) form active blastulae. 
3. Eggs left in sea-water 11 Ta ntes thence to ,M., KCN; thence to sea-water 
after the following intervals. 
a. 2hours. Blastulae few, but more than in Bl. 
b. S8hours. Blastulae more numerous than in a, but few as compared with B2. 
c. 4% hours. A small proportion of blastulae. 
B (+Ca). Eggs left for 5 minutes in 250 cc. 0.55 Mm KCNS + 15 ec. ™ CaCl. 
Thence returned to sea-water. Part left in sea-water, part treated with hyper- 
tonic sea-water. 
1. Eggs left in sea-water. Marked contrast to Bl. Great majority remain 
unchanged. A small proportion (more than in A (+Ca) 1) show membranes and 
irregular change of form; no larvae. _ 
After 22 hours eggs are fertilized: almost all develop normally; after 2 days the 
dish is full of vigorous plutei. 
2. Eggs left in sea-water 7 minutes; thence to hypertonic sea-water 380 minutes; 
returned to sea-water. Eggs are mostly unaltered next day, but the proportion 
broken down is higher than in the similar experiment with NaI. A considerable 
number of blastulae are formed. 
On fertilization after 22 hours most eggs form larve, but these are largely abnor- 
mal; few surface swimmers. 
Control experiments. Unfertilized untreated eggs remain unchanged. Fertil- 
ized eggs all develop normally. 
The above experiments show that brief exposure to pure isotonic 
sodium iodide or potassium sulphocyanate solutions has the effect 
of producing fertilization-membranes and initiating change of 
form or cleavage in the majority of eggs; but that if left in sea- 
water after such treatment nearly all die in an early stage of devel- 
opment; after eighteen hours such eggs appear broken down, 
coagulated and depigmented, proving the persistence of a condi- 
tion of increased permeability. Such persistence is in itself 
sufficient to account for the destructive effect of the treatment. 
On the other hand, if the eggs are treated, soon after return from 
the salt-solution to sea-water, with hypertonic sea-water for thirty 
minutes, a large proportion—in favorable experiments the great 
majority—form larvae, many of which swim actively at the sur- 
face of the water and develop into normal plutei. The rate of 
development of such larvae is fully equalto the normal. The early 
stages, however, always show certain characteristic abnormali- 
ties; the fertilization membranes are thinner than normal, the 
cleavage is usually irregular, and the blastomeres tend to have a 
more rounded form and to cohere less closely than in sperm- 
