30 A. OKA. 



to add. In the paper referred to above, Cori desei-ibos and lioiires the cells 

 that constitute the organ at various places : '' A'^on deui Leibeswandepithel 

 hebt sich das Trichterepithel deutlich durch die Helligkeit seines Plasmas ab. 

 An der freien Fliiche zeigen ferner die niifc langen Wiinperhaaren versehenen 

 Trichterzellen einen ausserst scharfen Kontour, der entsprechend die ein/el- 

 nen Zellen kleinen Unterbrechungen besitzt." He remarlcs further that the 

 nephridial canals are composed of cubical cells with round nuclei. As regards 

 his " unpaarer Ansfiihrungsgang " ho observes that the constituent cells, 

 which have no cilia, are flattened when the cavity is filled up with excretory 

 cells, l:)ut more or less cubical when it is empty. A little al)0ve the point of 

 unioii of the two tubes the nephridial Avail ceases to be ciliated. It is this 

 portion, which Cori calls the " Ausfiihrungsgang."' but, as miglit bo seen 

 from the diagrammatic figures of the entire organ, this name is little appli- 

 cable, at least in the case of PcctinatcJla. Indeed I have seen many longi- 

 tudinal sections of polypides that looked exactly hke the fig. 14 of Cori, but in 

 all of them the portion corresponding to Cori's " Ansfiihrungsgang " proved to 

 be nothing but a part of the body-cavity. An important character that ought 

 not to be omitted in the description of the nephridium of i'resh- water Tolyzoa 

 is that none of the constituent cells bear a glandular appearance. 



In describing this organ Braem tries to explain that its existence is due to 

 certain local circumstances of secondary importance and thus to disprove its 

 nephridian nature. Since the lumina of tentacles are all prolongations of the 

 lophophoral cavity, those of the median tentacles of the inner row must also 

 be brought into commuiiication with the latter. This takes place, according 

 to Braem, by means of the short tul;)es as the only way possible of fulfilling 

 the above condition, because the epistomial cavity preveiits the right and left 

 halves of the lophophoral cavity from uniting freely on the anal side. Thus, 

 the nephridial tubes, which he calls " Gabelkanal," are regarded as a struc- 

 ture caused by the presence of the epistomial cavity. In my opinion, this is 

 just the reverse of what seems to be in reality. It is not the epistomial 

 cavity that causes the nephridial tubes to be formed, ])ut it is the latter which 

 divide the body-cavity into the epistomial and lophoishoral cavities in the 

 upper portion of a polypide. If the "Gabelkanal" has no other function 



