386 Charles R. Stockard. 
tic anssthetic effects, but they are strikingly common in the 
alcohol solutions. On the other hand, similar abnormalities of 
the nervous system are really infrequent in the weaker Mg solu- 
tions. 
The slight effects of Mg on the development of the central 
nervous system are interesting when compared with the marked 
effects of other anzesthetics on these tissues. In this regard it is 
important to remember that in physiological experiments on nerve- 
muscle preparations Mayer (’08) has found that Mg acts directly 
as an inhibitor of muscular activity, exerting little if any effect on 
the activity of the nervous parts. The action of Mg in these 
experiments is not particularly on the nervous system but more 
largely on the dynamic processes concerned in the outpushing of 
the eyes. 
The occurrence of the several ophthalmic anomalies is common 
to all of the anesthetic solutions and similar conditions have not 
been found in embryos treated with various salts and sugars 
(06, ’07) which may inhibit general development and induce 
many other abnormalities. 
THE Errects oF CHLORETONE, ETHER AND CHLOROFORM ON 
DEVELOPMENT 
Chloretone, ether and chloroform when employed in weak 
solutions influence developing eggs in a way somewhat similar 
to that described for alcohol. The action of these substances is 
not so pronounced and may be described more as an inhibition of 
the general developmental processes. The embryos are usually 
small and recover very slowly from the inhibiting effects after 
being returned to sea-water. A few of the individuals in all 
these solutions exhibit the cyclopean defect in its various degrees 
just as it has been described in the specimens treated with alcohol 
and Mg. 
The ophthalmic defects, cyclopia, monophthalmicum asymme- 
tricum and entire absence of optic vesicles, are all conditions of 
arrested or inhibited development and are prevalent among 
embryos treated with solutions having anesthetic properties. 
