112 The American Naturalist. [February, 
2d, The manner in which polygamy may have originated. 
3d, The origin and effect of excessive pugnacity. 
4th, The origin and advantage of great sexual disparity. 
5th, The origin and advantage of the ability to endure long- 
protracted fasts. 
The sexual disparity, excessive pugnacity, and ability to en- 
dure*protracted fasts are all intimately related to polygamy, 
either as cause or effect. 
Up to a certain point pugnacity and disparity seem to have 
acted as causes of polygamy. Beyond that point they seem to be 
effects of polygamy, or at least are accelerated or intensified by it. 
The ability to endure long fasts would seem to be purely an 
effect of polygamy. 
ON THE GENESIS OF THE CHROMATOPHORES 
IN FISHES.’ 
BY CARL H. EIGENMANN. 
FoR several reasons pelagic eggs are more available for a study 
of the phenomena of color-formation than fixed eggs. Pigment 
is nearly always formed in pelagic eggs some time before hatching, 
and as the embryonic life is usually short and the eggs are trans- 
parent, the whole process from fertilization to hatching can be 
observed, without any great inconvenience, in the living egg- : 
In all pelagic ova with oil-globules observed by me pigment 1s 
deposited in certain cells before the time of hatching. In the 
eggs of three species of pelagic ova (Stolephorus) without oil- 
globules no pigment is formed several hours after hatching, while 
in Mierasfer dubius (?) without oil-globules, pigment is present 
the time of hatching. 
Only three colors have been observed in the eggs examined, vr 
black, a brownish-yellow, and bright yellow. In the vanont. 
species of Sebastodes (viviparous) only black pigment is formed, | ; 
while in Atherinopsis black pigment alone is observed until pase : 
1 Notes from the San Diego Biological Laboratory, IV. 
