GENERAL BIOLOGY 



739 



seemed far to exceed that of the pelagic fish eggs ; this also appears 

 to have been the case with the catches of ^ 

 the German Plankton Expedition, but these 

 catches were very small. The scarcity of 

 fish eggs and the abundance of pelagic fish 

 fry might appear to indicate a continuous 

 production of rapidly hatching eggs, the 

 larval and post-larval stages being of much 

 longer duration, but a study of the ovaries 

 of the adult fishes does not favour this sup- 

 position. In Cyclothone, for instance, the 

 eggs seem to be equally developed in every 

 portion of the ovary, and to ripen through- 

 out the entire length of the ovary at the 

 same time. During our cruise the ovaries 

 were found to be ripest at Stations 53 and 

 64 on the southern section. 



Any observer previously acquainted only 

 with the spawning of large boreal fishes 

 must be strongly impressed by the appear- 

 ance of the minute, sexually mature, oceanic 

 fishes. Figs. 526 to 529 represent some 

 ripe fish of genuine oceanic types and their 

 ovaries. In the laterally compressed Argy- 

 ropelecus hcmigyvinus (Fig. 526), the ovaries, 

 containing only a few hundred eggs, lie 

 wholly or partly above one another, and the 

 full-grown individual, the ovaries of which 

 approach ripeness, is only 3.4 cm. long. 

 Cyclothone signata (Fig. 527) becomes sexu- 

 ally mature when 3 or 3.5 cm. in length, 

 the aggregate number of eggs contained in 

 both ovaries being about 1000. Cyclothone 

 microdon (Fig. 528), on the whole a larger 

 species, becomes mature when about 6 cm. 

 in length, the ovaries containing a total of 

 about 10,000 eggs. A specimen of Photo- 

 stoniias guernei 10.8 cm. in length had, 

 according to Collett, about 400 eggs in 

 each ovary. Gonostoma grande had, accord- 

 ing to Collett, 2798 eggs. On the other 

 hand, the larger pelagic fishes from deep water, like Gastro- 

 stonius bairdii (see Fig. 529), have many eggs, but they 



Fig. 527. 



Cyclothone signata, Garm. 



Nat. size, 3.5 cm. 



