74 S. GOTO. 



described by Pintner, which is situated outside the cuticular mem- 

 brane. But to me it seems that the mere presence of a cuticle is 

 morphologically a quite unimportant matter, so that the " Aussen- 

 epithel " of Pintner is as truly an epithelium as that of the ex- 

 cretory canals of the Nemertinei, just as the cells that produce the 

 chitinous wall of the trachea of insects are as truly of an epithelial 

 nature as any others that do not secrete chitin. Then as to the dif- 

 ference of the terminal " Kolben " of the Nemertinei from the 

 terminal excretory cells of other flat-worms, it seems to me that this 

 is also of quite a secondary significance ; that an organ consists of a 

 single cell does not afford, it seems to me, any more reason against its 

 homology with a multicellular organ than the fact that an organ 

 consists of five cells is any ground against its being homologous with 

 another consisting of six cells. If, on the other hand, we do not take 

 into account the number of cells, there is a striking similarity between 

 the terminal excretory organs of the Nemertinei and other Plathel- 

 minthes. I therefore believe that the excretory systems of the 

 Plathelminthes, the Nemertinei inclusive, have all been derived from 

 the same primitive form, in other words, that they are homophylous. 

 To recapitulate the above discussion, it is my opinion that the 

 term " intracellular " is quite inappropriate to the excretory system 

 of the Trematodes and the Turbellaria, as it gives occasion to much 

 misapprehension and prevents the true understanding of the exact 

 state of the matter. It is also my opinion that the excretory systems 

 of the Nemertinei and the other Plathelminthes are phylogenetically 

 of the same origin, the number of cells that compose the various 

 parts of the system being of quite secondary importance in discussing 

 its phylogeny.'^ 



1 ). Whitman, from a totally different point of view, comes to the same conclusion. He says, 

 " The nephrostome is a nephrostome all the same whether it consists of one cell, two cells, 



