70 



are likewise deeply tinged with red. Possibly the blacks 

 and greens which prevail among the inhabitants of other 

 colored bottoms are likewise dependent upon coloring mat- 

 ter which is absorbed with the food. Gunther believes that 

 the pink color in the flesh of the salmon is due to the absorp- 

 tion of the coloring matter of the crustaceans they feed 

 upon. 



The brilliant coloration of many kinds of fishes during the 

 breeding season may possibly have a relation to sexual selec- 

 tion ; indeed, this can scarcely be doubted by any one who 

 has observed the peacocking moments of male fishes. It has 

 also a physiological significance which it is not difficult to 

 comprehend. The increased brilliancy is usually most mani- 

 fest in those parts of the body which lie close to the repro- 

 ductive organs, which is often flushed and vivid in color, in 

 the ventral fins, and in less degree in the sides of the body 

 and the posterior and lower parts of the head. The entire 

 vascular system is in a condition of extreme activity at this 

 time, as is evident from the manner in which outgrowths of 

 the head and teguments are so rapidly developed. Every 

 pigment cell is receiving an unusual supply of blood, and its 

 more abundant nutrition is in part at least the cause of its 

 brilliancy. 



If an abundant supply of blood results in an increase in 

 brilliancy, its withdrawal from the teguments, on the other 

 hand, causes an immediate decrease. I have often watched 

 the large brightly striped groupers, {Epinephehis striatiis) 

 confined in the crystal fish pools in Bermuda. When one of 

 these had swallowed a large morsel of food its color became 

 almost instantly lighter and duller. This was evidently the 

 result of the rush of blood to the stomach, to take part in the 

 work of digestion : in like manner a man's face sometimes 

 becomes paler after he has eaten a hearty dinner. 



The dullness and pallor in the color of fishes after death is 

 due to the absence of living blood from the chromatophores. 

 If, however, a fish not long dead is placed in the sun, its color 



