322 H. H. NEWMAN. 



lost. In about twenty minutes he was as dark and as brilliant 

 as before and had succeeded in ousting the usurper from his 

 domain, although not without repeated struggles in which his 

 victory became more decisive each time. The next day the same 

 male was in control, but on the following day another male of 

 medium size had acquired supremacy. It is probable that the 

 period of sexual climax is of short duration, not exceeding three 

 or four days. A male at the very height of his sexual activity is 

 afraid of nothing and is practically invincible. 



This account will serve as a sample of the scenes observed 

 repeatedly in the aquaria and in natural conditions during the 

 months of June and July. The last recorded observation of 

 spawning in this species was taken on July 7, although ripe 

 males and females were found for at least two weeks later. 



This account of the spawning behavior of Fundulus heteroclitus 

 may well be concluded with an account of a few more experi- 

 ments and some additional isolated observations. 



Experiment i. - - A considerable number of actively spawning 

 males and females were separated into two aquaria, the males in 

 one and the females in another. Inside of about fifteen minutes 

 the males had all become nearly as pale as the females and spent 

 their time in wandering about uneasily as though seeking for a 

 place of escape. The females, on the other hand, seemed to be 

 very little affected by the absence of the males but went on ex- 

 truding eggs as freely as if the males had been present. It is 

 probable that the initial stimulus to egg extrusion given by the 

 males lasted some time after the removal of the latter. The 

 eggs were always eagerly devoured either by the female that 

 laid them or by another that rushed up and siezed them before 

 she could turn around. It is hardly probable that eggs are so 

 eagerly devoured in the open, as the food supply is not restricted 

 as in an aquarium. 



Experiment 2. --An aquarium was prepared with mud and 

 stones on the bottom to approximate natural conditions, and in 

 it were placed five spawning fish of each sex. These fish, instead 

 of appearing to enjoy their new surroundings, lost all interest in 

 spawning and spent all of their time in exploring their environ- 

 ment. In the meantime the males lost all of their " spawning 



