156 THE STORY OF FISH LIFE. 



berth ; out people walking in the sea with bare 

 feet often step upon this fish, and the poison is 

 injected into the wound by the pressure of the 

 foot on the poison bags. So virulent is the 

 action of this poison that death is not infrequently 

 the result. 



But the most perfect poison organs yet dis- 

 covered are those of a genus of frog-fishes 

 (Thalassophryne) of Central America. Here, as 

 in the weaver of our own shores, the poison 

 spines are those of the operculum or gill-plate, 

 and of the dorsal fin. These spines are hollow, 

 and resemble the poison fangs of the snake. 

 They are perforated at the base and tip. The 

 base of the spine is embedded in a poison sac 

 filled by the secretion of a fluid from its inner 

 walls. As these sacs are not provided with 

 muscular tissue, it is supposed that they must 

 discharge their contents down the hollow spine 

 as a result of the pressure of the spine when it 

 enters the body of the victim. 



In many cat-fishes there is found a very re- 

 markable apparatus, which it is believed repre- 

 sents a poison organ. "Some of these fishes," 

 observes Dr Giinther, " are armed with powerful 

 pectoral spines, and justly feared on account of 

 the dangerous wounds they inflict ; not a few of 

 them possess, in addition to the pectoral spines, 

 a sac with a more or less wide opening in the 

 axil of the pectoral fin, and it does not seem 

 improbable that it contains a fluid which may 

 be introduced into a wound by means of the 

 pectoral spine, which would be covered with it, 

 like the barbed arrow-head of an Indian. How- 



