iv EXPERIMENTAL TERATOGENY 193 



ascidians, molluscs, worms, crustaceans, some aquatic 

 insects, while frogs and fishes die when subjected to 

 high pressures which the former easily withstand. 

 I cannot enter here upon the details of the experi- 

 ments or their results, nor upon the reason of these 

 differences between different species, but the fact of 

 latent life must be recorded. In experiments on the 

 influence of environment such circumstances contrary 

 to the continuation of life must be avoided ; they 

 may be induced by other factors, such as change of 

 chemical medium, for instance (in the case of micro- 

 organisms), and it suffices to notice the fact. 



In some cases external influences may make them- 

 selves felt by creating animals or plants which are 

 abnormal and monstrous. Although in most cases 

 life is impossible, through the importance of the 

 disorders thus introduced, these facts are interesting, 

 as they go to show that very slight influences may 

 make themselves felt in a marked manner, when they 

 are allowed to operate at certain periods of life, 

 especially during that of early development, which is 

 the only period during which real monsters may be 

 produced. 



Among the physiologists who have investigated 

 the question of experimental teratogeny, of the 

 artificial production of monsters, none deserve 

 mention more than Camille Dareste, the author of 



O 



