Adaptations of Fishes 57 
These alkaloids are most developed in the ovaries and testes, 
and in the spawning season. Thev are also found in the liver 
and sometimes elsewhere in the body. In many species other- 
wise innocuous, purgative alkaloids are developed in or about 
the eggs. Serious illness has been caused by eating the roe of 
the pike and the barbel. The poison is less virulent in the 
species which ascend the rivers. It is also much less developed 
in cooler waters. For this reason ciguatera is almost confined 
to the tropics. In Havana, Manila, and other tropical ports it 
is of frequent occurrence, while northward it is practically un- 
known as a disease requiring a special name or treatment. On 
the coast of Alaska, about Prince William Sound and Cook Inlet, 
Fic. 41.—Numbfish, Narcine brasiliensis Henle, showing electric cells. 
Pensacola, Florida. 
a fatal disease resembling ciguatera has been occasionally pro- 
duced by the eating of clams. 
The purpose of the alkaloids producing ciguatera is con- 
sidered by Dr. Pellegrin as protective, saving the species by the 
poisoning of its enemies. The sickness caused by the specific 
poison must be separated from that produced by ptomaines and 
leucomaines in decaying flesh or in the oil diffused through it. 
Poisonous bacteria may be destroyed by cooking, but the alka- 
loids which cause ciguatera are unaltered by heat. 
It is claimed in tropical regions that the germs of the bu- 
bonic plague may be carried through the mediation of fishes 
which feed on sewage. It is suggested by Dr. Charles B. Ash- 
