ARTIFICIAL PRODUCTION OF NoRMAL Larve 617 
was always changed in both classes of eggs simultaneously, 
and the chances for fertilization of the eggs from sperma- 
tozoa contained in the sea-water were equal for both. If the 
sea-water had contained any spermatozoa capable of impreg- 
nating the eggs, those eggs that had been in solutions with 
less MgCl, should have been fertilized first. 
4. In almost all the experiments eggs were taken out 
of the mixture of 60 to 50 cc. %9 n MgCl, +40 to 50 cc. 
sea-water at different periods. In no case did a single egg 
develop into a blastula that had been in this solution for less 
than one half-hour, and generally only those eggs yielded 
blastule that had been in this solution for about two hours. 
If the sea-water had contained spermatozoa, the latter should 
have fertilized those eggs first which had been a shorter time 
in the artificial solution. On the other hand, the eggs that 
had been left in the artificial solution more than two and 
one-half hours as a rule yielded fewer or no blastule. 
5. I stated above that even at the height of the spawning 
season eggs are rarely fertilized by spermatozoa contained in 
the running sea-water. I do not think one would be likely 
to see more than one egg in a thousand undergo develop- 
ment under such conditions, provided that no contamination 
through the instruments occurred. In our experiments which 
were made at the end of the spawning season about 20 to 50 
per cent. of the eggs that had been kept in the right solution 
developed. It is out of the question to attribute such a 
result to spermatozoa contained in the sea-water. 
6. As far as I can see, there is only one possible source 
of error left. It might be that the sea-water contained 
spermatozoa, but that these spermatozoa were not able to 
fertilize normal eggs, while a treatment of the egg with 
the mixture of 60 c.c. 22 MgCl, + 40 c.c. sea-water in- 
creased its susceptibility to impregnation, or a treatment 
of the spermatozoon with the same solution increased the 
Digitized by Microsoft® 
