269 



PART IV. 



VENOMS IN THE ANIMAL SERIES. 



CHAPTER XVI. 



1.— INVERTEBRATES. 



Besides reptiles, many other animals possess poison-glands 

 and inociilatory organs which they employ, either to defend them- 

 selves against their natural enemies, or to capture the living prey 

 upon which they feed. 



The venoms that they produce are still, for the most part, but 

 little understood. A few of them, however, have excited the 

 curiosity of physiologists, especially those secreted by certain 

 batrachians, such as the Toad, and certain fishes, such as the 

 Weever. Some of them exhibit close affinity to snake-venom, and 

 are composed, like the latter, of proteic substances modifiable by 

 heat and precipitable by alcohol ; others possess altogether special 

 characters, and resemble alkaloids. 



The lowest animal group in which these secretions begin to be 

 clearly differentiated is that of the Coelenterates. 



A. — Coelenterates. 



It has been shown by Charles Richet^ that the tentacles of sea- 

 anemones {Anemone scultata) contain a toxic substance which has 



' Comptes renclus de la Societe de Bioloyic, December 13, 1902 ; June 6, 

 July 25, 1903 ; February 20, 1904. 



