66 S. GOTO. 



mentioned, divided into two groups, digestion is, according to 

 Grraff,'^ exclusively carried on intracellularly. It is allowable, how- 

 ever, to suspect whether the secretory cells have not been overlooked 

 in some forms, especially in those in which the salivary glands form 

 only a single group opening on the surface of the pharynx. One 

 may, again, regard the " kolbenfdrmige Gebilde " of Distomum Wester- 

 mani as secretory cells, and bring them forward in opposition to our 

 assumption ; since in this species the true salivary glands are pi'esent. 

 But if our assumption be true, there would be a time in the phylogeny 

 of the glands in question when both the true salivary glands and the 

 secretory cells of the intestine would discharge their functions side by 

 side. It may also be said in the way of objection to our assumption, 

 that food granules are observed in the intestinal cells, and that this 

 makes it very probable that these cells have the power of digesting 

 them. But it seems to me that these granules are not the product of 

 a simple disintegration of the swallowed food, but that they have been 

 produced by the action of a certain (partially?) digestive fluid; and 

 moreover it may be suspected whether these granules are not, as sug- 

 gested by Greenwood"', formed secondarily in the cells, and whether 

 they are not taken in primarily in the fluid form. 



7. The Excretory System. 



The excretory system is constructed on the same fundamental 

 plan in all the genera treated of in this paper, and presents only some 

 slight deviations in different genera. In all of them, there are two 

 main vessels on each side of the body, which are directly continuous 

 with each other at the posterior end. They run, roughly speaking, 

 on the ventral side of the intestine between it and the ventral nerve ; 



1). Graff — Monographie, p. i 

 2). Greenwood— Z. c. p. 323. 



