Effect of Aleohol and Anzsthetics. 387 
The writer is led to conclude, therefore, that his former hypo- 
thetical explanation of why cyclopia occurred in embryos treated 
with Mg solutions was correct. The evidence strongly indicates 
that the ophthalmic abnormalities produced in these experiments 
are the result of an anzsthetic action during the early develop- 
mental stages. 
THE PERIOD OF DEVELOPMENT AT WHICH CYCLOPIA MAY BE IN- 
DUCED BY CHEMICAL AGENTS 
The Mg experiments were repeated mainly to ascertain at 
how late a period in development eggs could be subjected to the 
solutions and subsequently develop into cyclopean monsters. 
The original experiments seemed to demonstrate the fact that 
eyclopia was due to external influences acting on the development 
of the optic vesicles, and not in any sense to a germinal variation. 
Nevertheless, H. H. Wilder (08) in the face of these results, 
advanced a germinal theory to account for the origin of cyclopia 
and attempted to explain away the obstacle offered in the experi- 
ments referred to by claiming that the eggs were subjected to the so- 
lutions at so early a stage in development that germinal variations 
might still have been induced. This is impossible, asthe writer has 
pointed out elsewhere (’09b), since germinal variations may only 
be induced before embryonic development has begun. After 
the two-or four-cell stage (the time at which the eggs were sub- 
jected to Mg) is reached any thing done to the egg has its effect 
on the developing embryo to cause this or that abnormal condition. 
The only germinal variation possible at such a period would be in 
the primordial germ cells of the developing individual, a variation 
which would not manifest itself until the next generation of 
individuals. 
The following experiments prove beyond doubt that cyclopia 
may be produced by the action of environmental influences. 
When eggs in the eight-cell stage, or three and one-half hours 
after fertilization, are subjected to the action of Mg solutions 
many of the resulting embryos will show the cyclopean defect. 
