' LOVE-MAKING AMONG FISHES i8i 



Briefly, before the male commences his search for a mate 

 he constructs a nest of fine fragments of aquatic weeds, 

 which are held together, not by interweaving as with 

 birds' nests, but by a sticky and copious secretion from 

 the kidneys. According to some authorities, this secretion 

 is to be regarded as a pathological product caused by the 

 undue pressure of the ripening testes. It is difficult to 

 accept this interpretation, for it might with as much 

 reason be argued that the copious secretions of the sali- 

 vary glands of the edible Swift — which builds a nest 

 constructed entirely of hardened saliva — are also patho- 

 logical in character. But be this as it may, the nest 

 completed, the male seeks a mate, or mates, for polygamy 

 is the rule of his tribe. In his search for these he has 

 constantly to do battle with other males, whom he 

 endeavours to disembowl by swift rushes contrived to 

 rip open his rival as he passes, by means of one or other 

 of the erectile spines which project from his back and 

 belly. With the females whom he desires he uses the 

 arts of peaceful persuasion, swimming backwards and 

 forwards before her in his endeavour to excite her 

 amorous instincts. At last he persuades her to enter 

 his bower and deposit a few eggs, fertilizing them 

 immediately they are laid. The first to enter leaves by 

 forcing a passage through the opposite wall of the nest, 

 a happy contrivance, for thereby a current of water can 

 be constantly driven through, leaving fresh oxygen to 

 the developing eggs. One female after another is inveigled 

 into the bower, until the complement of eggs is complete. 

 These, singularly enough, are now taken charge of by the 

 male. He it is who creates life-sustaining currents which 

 bathe the eggs, by the rapid vibrations of his breast- 

 fins, and he it is who protects them from their most 



