FISHES. 



281 



the others. All are singular among fishes in their mode of building a nest, and the 

 provision which nature has made for such a task. It is the male alone that is the 

 nest-builder, and he is provided with a special organ or gland. According to Mr. 

 John A. Ryder, this secreting gland is " a large vesicle filled with a clear secretion, 

 which coagulates into threads upon contact with water. It appears to open directly in 

 front of the vent." " As soon as it is ruptured it loses its transparency, and what 

 ever secretion escapes becomes whitish after being in contact with water for a short 



Fig. 156. — Gaaterosteus aculeatus and SpinacMa spinachia, sticklebacks. 



time. This has the same tough, elastic qualities as when spun by the animal itself, 

 and is also composed of numerous fibres, as when a portion is taken which has been 

 recently spun upon the nest." Thus provided, when the nuptial season has arrived, 

 the male stickleback prepares to build his nest wherein his mates may deposit their 

 eggs. How this nest is built, and the subsequent proceedings of the stickleback, have 

 been told us in a graphic manner by Mr. John K. Lord, from observations on a 

 western American species, although the source of his secretion was misunderstood. 



