k 



OX THE NErHEIDITTM OF PHYLArTOLAIIATATOUS POLYZOA. 20 



The iineqiiality in tlie thickness of the wall disappears in fig. 7, where the 

 lateral portion is just so thick as the median. Fig. 8 shows how the Imnina 

 of the next-mediaii tentacles of hoth sides open into the cavity of the nephri- 

 dinm. It is one of snch openings that Cori figures and describes under the 

 name of " Nebentrichter." In fig. 1) the two tubes are united into a single 

 tube, with the lumina of the next median tentacles on both sides. Fig. 10 

 is like the preceding one in every respect, except that the single tube stands 

 in communication with the exterior by means of a small opening. In fig. 11 , 

 which is the uppermost of the series, we have no trace of the nephridial 

 tube, Init in its ]ilace we find the lumina of the innermost tentacles. A re- 

 co]istruction fi'om these sections shows tliat the cavity of the nephridium 

 ojiens into the lophophoral cavity by means of the funnels, communicates 

 with the exterior through a small opening in the;n)ody-wall, and is at the 

 upper extremity continuous with the lumina of four (sometimes five) inner- 

 most tentacles of the inner row. 



As shown above, my researches lead me to conclude that the statements 

 in my former paper with regard to the connection of the median tentacles 

 with the nephridium were correct. In his second paper Cori criticizes m)' 

 observations on this point in the following words; " Es diirfte audi in diesem 

 Falle ein Untersuchungs fehler, was die Verbindung des genannten Organs 

 mit den Tentakeln l)etrifft, vorliegen, wie auch in I'ezug auf das Fehlen der 

 ausseren Offiiung." I am ready to acknowledge the correctness of this re- 

 mark, as far as concerns the presence of the external opening, but as to the 

 first part, it is difficult for me to accept its validity. The figures in Cori's 

 own paper, especially the figures 6-10, can not l)e interpretted as showing 

 the continuity of tentacular lumina with the loiDhophoral cavity outside the 

 nephridial tubes. It is, however, no easy task to observe the true bearings 

 of these cavities, for in a majority, of individuals, the floating cells or the 

 leucocytes, of which I will speak afterw.irds, are accumulated in masses at 

 the bases of the tentacle's, making the communication of the latter with 

 the nephridial tube extremely obscure. And it was no doubt this circum- 

 stance that caused the difference in our statements. 



As to the histological structure of the nephridium I ba-ve nothing nevy 



