510 



H. H. Neivman 



regions. A sort of steelv glint, somewhat akin to iridescence 

 suffuses the body. On certain well-defined regions of the body 

 appear many characteristic, somewhat stiff, papillae that are readily 

 visible to the naked eye. These papillae are temporary organs 

 of definite structure, that appear only during the spawning season 

 and disappear afterward. They occur on dorsal and anal fins, 

 on the cheeks, and on the sides, regions that come into most 

 intimate contact with the body of the female during the act of 

 spawning. These papillae I have chosen to call "contact organs." 



In the female the body becomes paler than usual, the flesh 

 becomes soft, the fins soft and pliable, and the abdomen dis- 

 tended with eggs. They also show a coyness of behavior that 

 seems to incite the males. 



The spawning act proper, as observed both in aquaria and 

 in the open, is essentially a clasping phenomenon. The male 

 pursues and corners the female, crowds his body against hers and 

 clasps her just anterior to the tail with his large, strong, and 

 especially modified dorsal and anal fins. While united in this 

 fashion, both bodies bent laterally into the shape of a flattened S, 

 the tail regions vibrate rapidly for from one to three seconds and 

 eggs and milt are simultaneously extruded in close proximity to 

 one another, thus insuring fertilization. An account of courtship, 

 rivalry and display, previous to spawning, while of some interest, 

 would take us rather far afield at present. In a former paper 

 these subjects are fully treated. 



This study of spawning behavior and the physical signs of 

 high sexual tone explained some of the earlier contradictions 

 and ill success and served greatly to improve the methods used. 



2 The Importance of Equalizing the Physiological Condition 



of the Parents 



Experience showed what ordinary judgment should have sug- 

 gested that, if one wishes to eliminate the factors of over-and 

 under-ripeness, staleness, etc., of sexual products, it is necessary 

 to cross-fertilize only during the period when both species are at 

 their sexual prime. Only if this precaution be observed can one 

 obtain in different experiments even approximately uniform results. 



