EMBRYOLOGY OF CRYPTOBRANCHUS 85 



tended with eggs. When removed and measured by displacement 

 of water, the stomach and its contents were found to have a bulk 

 of over 200 cc. The mouth also was full of eggs, and strings of 

 eggs protruded from the pharyngeal openings. The quantity of 

 eggs present seemed to represent almost an entire spawning. 

 The feat of swallowing such a quantity of eggs would seem pos- 

 sible only if they were taken before the swelling of their envelopes. 



The digestive processes of the hellbender are extremely slow, 

 and I have taken undigested eggs from the stomach a week after 

 they were eaten. Under these conditions the presence of a single 

 male hellbender in the nest is in the main protective. On account 

 of the small number of eggs eaten at once, and the slowness of his 

 digestive processes, fewer eggs are eaten than would be the case 

 if other hellbenders, and especially the spent females, had free 

 access to the nest. 



As previously noted, a male has been observed to fight and drive 

 away a spent female and several males that were attempting to 

 enter the nest. The male in such cases has the advantage over 

 the female because of the weakened condition of the latter; as 

 regards the other males, he has the advantage of position. 



The facts suggest that the male, in thus driving away others of 

 his own kind, may be primarily concerned in guarding his own 

 food supply; this guarding habit may become modified into a true 

 brooding instinct. But it is difficult to believe that the male, 

 after having filled his stomach with eggs, would any longer be 

 concerned with the fate of the remaining eggs on account of their 

 value as food. 



According to the second interpretation, the male may hold the 

 nest in expectation of the coming of another ripe female; an exten- 

 sion of this habit may give rise to the brooding instinct. Accord- 

 ing to this view, the brooding instinct has its origin in the breeding 

 habit. 



The reception of a ripe female by a male guarding eggs has not 

 been directly observed, but the following data afford sufficient 

 evidence on this subject: Out of twenty-nine nests examined 

 during the seasons of 1906-1911 inclusive, eleven were found to 

 contain eggs of at least two different spawnings, the product of 



