190 



FISHES. 



are found to be eatable if the head and intestines be removed 

 immediately after capture. In the West Indies it has been 

 ascertained that all the fishes living and feeding on certain 

 coral banks are poisonous. In other fishes the poisonous 

 properties are developed at certain seasons of the year only, 

 especially the season of propagation : as the Barbel, Pike, 

 and Burbot, whose roe causes violent diarrhoeas when eaten 

 during the season of spawning. 



Poison-organs are more common in the class of Fishes than 

 was formerly believed, but they seem to have exclusively the 

 function of defence, and are not auxiliary in procuring food, as 

 in venomous Snakes. Such organs are found in the Sting-rays, 

 the tail of which is armed with one or more powerful barbed 



Fig. 98. — Portion of tail, \vith spiues, of Aetobatis narinari, a Sting-ray 

 from the Indian Ocean, a, nat. size. 



spines. Although they lack a special organ secreting poison, 

 or a canal in or on the spine by which the venomous fluid is 

 conducted, the symptoms caused by a wound from the spine 

 of a Sting-ray are such as cannot be accounted for merely by 

 the mechanical laceration, the pain being intense, and the 

 subsequent inflammation and swelling of the wounded part 

 terminating not rarely in gangrene. The mucus secreted 

 from the surface of the fish and inoculated by the jagged 

 spine evidently possesses venomous properties. This is also 

 the case in many Scorpoenoids, and in the Weaver ( Trachinus), 

 in which the dorsal and opercular spines have the same 



