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Bulletin Wisconsin Natural History Society. [Vol. 5, No. 2. 
solutions and from 8% and 9% solutions of alcohol. There were 
none from the other solutions. 
No division occurred after the immersion of spermatozoa in 
weak (.001:%) solutions of ammonium hydroxide. 
When inactive sperm of Asterias or of Arbacia is immersed 
in solutions of alcohol, ether or ammonium chloride in sea-water, 
it not only becomes active, but in some cases is rendered capable 
of fertilizing eggs not normally fertilized by the same sperm. 
Fertilization did not always take place, even when the spermatozoa 
became active and surrounded the eggs on being added to them. 
In order to discover whether the eggs or the sperm, were 
responsible for this lack of fertilization, a series of experiments 
was carried out, in which the eggs of two females and the sperm 
of two males, was used. The eggs were ripe and in good condi- 
tion. The spermatozoa were altogether inactive and did not 
normally fertilize the eggs. Eggs and sperm were used inter- 
changeably, as shown in Table V, p. 121. 
After immersion in solutions of alcohol, ether, and ammonium 
chloride, as indicated in Table V, the inactive spermatozoa of both 
males became active. The spermatozoa of IMale I fertilized the 
eggs of both Female I and Female II, except after immersion in 
10% alcohol solutions, and, in one case, an immersion in 2% 
ether. [See (d).] 
The spermatozoa of Male I did not in any case fertilize the 
eggs of Female I, but in all cases, except after immersion in 10% 
alcohol, they fertilized the eggs of Female 11. 
After fertilization by the spermatozoa of Male I, immersed in 
1% solutions of alcohol and of ether for five minutes, 50% to 
95% of the eggs of Female I and of Female II divided, and t% 
divided after an immersion of the spermatozoa in o.t% NH^Cl. 
A small number only divided after fertilization by spermat- 
ozoa immersed in the stronger solutions for the same length of 
time; and, with one exception [See 6], none divided after immer- 
sion in the strongest solution used. 
After fertilization by the spermatozoa of Male II. immersed in 
I % alcohol for five minutes, 80% of the eggs of Female II divided. 
