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A Seasonal Study of the Kidney of the Five-Spined 

 Stickleback, Encalia Inconstans Cayuga Jordan. 



Walter N. Hess — DePauw University. 



During the greater part of the year the male kidney is an excretory 

 organ. At the breeding season, however, the kidney tubules, for about 

 one-third of their extent, as well as the urinary ducts, the bladder and 

 the common urinary duct become modified for the purpose of producing 

 slime. This secretion, which is used by the fish in constructing its nest, 

 is produced entirely by the male kidneys and only at the breeding season. 



In the process of slime secretion, the behavior of the nuclei is such 

 that they evidently pour into the cell bodies certain products, in the 

 form of secretion granules, which function in breaking down the gran- 

 ular cytoplasm of the cells, and thus form the secretion. These secre- 

 tion granules appear to be produced from certain products of the kary- 

 oplasm, as this substance gradually diminishes in amount during this 

 process. Since the nuclei become irregular and flattened, it is possible, 

 but not probable, that the nucleolus functions in this process. 



Only one kind of secretion is produced for constructing the nest. 

 This material is not silk, nor is it composed of fine fibrils, but appears 

 as a fine granular slime-like substance. It is sometimes exuded in 

 ribbon-like masses, but it probably functions more as an adhesive sub- 

 stance, than as a string, in binding the materials of the nest together. 



At the end of the breeding season the cytoplasmic granules arc 

 regenerated. They begin to appear on all sides of the nucleus at the 

 time that the nucleus begins to enlarge and become spherical. Since they 

 form about the nucleus and wander into the other parts of the cell it 

 would seem that the nucleus must be the active agent in their formation. 



During the resting or winter stage the cells which form the slime 

 during the spring appear much like the cells near the glomeruli which 

 secrete urine, except that their nuclei are much smaller and they contain 

 only one nucleolus. At this season the nuclei of the urinary secreting 

 cells are very large, often occupying at least half of the cell contents. 



