158 I. IJIMA : HEXACTINELLIDA. I. 



On the whole, these ideas of Schulze concerning the nuclei 

 do not differ from those expressed by him before with regard to 

 the smaller and the larger nuclei in the trabecuhe of E. asper- 

 g ilium, mentioned and remarked upon respectively by me under 

 (1) and (2) on pp. 153-154. This might naturally follow, if, as I 

 have assumed, the cells with granular contents in E. aspergillum, 

 mentioned by Schulze and referred to by me under (3) on p. 155, 

 are the same kind of cells as the ' Knollen ' cells of Schulze 

 (thesocytes) ; for, in that case, the nuclei without the ' Knollen ' in 

 8. arctica would have in E. aspergillum nothing to correspond to 

 but the nuclei I have mentioned under (1) and (2). A new point 

 is that the cells represented by the ' smaller nuclei ' in the 

 trabecular, or by at least some of these nuclei, are possibl}^ iden- 

 tical with the * Knollen ' cells or (according to my interpretation) 

 thesocytes. The implication is that one of these two kinds of cells 

 may be directly derived from the other. Tliis seems to me 

 highly improbable ; for, I think I have grounds to believe that 

 the thesocytes arise, on the contrary, from the so-called ' larger 

 nuclei ' of Schulze. 



In attempting to establish my position here taken, I will 

 begin by stating that I can not help entertaining a doubt as to 

 whether the size given by Schulze for the ' larger nuclei ' found 

 in the trabeculœ refers to real nuclei, — if a certain mistake is not 

 here involved in spite of his wonted accuracy in observations. 

 According to him, they should be 3-4 ij. large (against ca. 2 // of 

 the nuclei of ' Knollen ' cells ; 19'«, p. 08). To S2:>eak from my 

 own experience, the nuclei in the trabecular irrespective of their 

 having a well delimited cell-body or not, are all tolerably uniform 

 in size and general appearance within the limit of the same 

 Hexactinellid species at least, if not of the entire class. They 



