124 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



droplet, which frequently distends the cell to an almost 

 spherical form. 



At the point of union of the terminal cell and the capil- 

 lary tube with which it communicates the former is indented, 

 and from the base of this depression a slender cilium arises, 

 whose rapid vibration drives a transparent fluid, containing 

 a few highly refractive granules, down the tube. Through- 

 out the first part of its course the walls of the latter are 

 relatively thick, and the lumen pursues a very wavy course, 

 becoming more direct after several such canals have united 

 into a larger tubule. 



The products which these tubes convey are finally dis- 

 charged into the main canals, two in number, which 

 traverse almost the entire length of the animal (fig. 19). 

 Anteriorly each swells into a reservoir, from which a slen- 

 der duct extends outward and forward, to open by a 

 minute pore on the dorsal surface (fig. 11). In stained 

 preparations the terminal section of this canal presents a 

 puckered appearance, and at times contains a slight amount 

 of some secretion which stains darkly, bringing the pore 

 into sharp relief. 



Considerable variation exists among the smaller tubes 

 which discharge into the main canals, but fig. 19 represents 

 a fairly typical arrangement. Invariably a relatively large 

 vessel arises from the anterior extremity of each reservoir, 

 and after passing in front of the pharynx the two unite and 

 on the median line give rise to a short canal which bifurcates 

 and rapidly breaks up into a number of minute branches. 

 These extend to the anterior borders of the body, in among 

 the nerve-cords arising from the brain, over and through 

 the tissues of the pharynx, and in some individuals a com- 

 paratively extensive system drains the wastes from the region 

 occupied by the reproductive organs in front of the ovary. 

 This latter area may also be traversed by branches from 

 other vessels arising on the inner side of each reservoir. 

 The latter may also develop on their outer borders out- 

 growths which extend outward among the yolk-glands 

 and branches of the intestine to the margin of the body. 



