STRUCTURE AND DIOVELOPMENT O]." COEEOPLANA. 23 



becoming the central filament. 



As regards the development of the colloblast, we have opinions of 

 Samassa (92), Schneider (02) and Abbott ('07), which disagree much 

 with one another. Samassa maintains that, a colloblast originates from 

 two formative cells situated close to each other in the tentacle-basis, 

 and one of them which is glandular, develops into the head of the 

 colloblast, while the other which is a kind of interstitial cell, gives rise 

 to the central and spiral filaments. The forming processes of those parts, 

 however, are not given in detail. He states, for the concluding remark:- 

 " Durch vorstehende Darstellung glaube ich erweisen zu haben, dass das 

 man bisher als Greifzellen betrachtete, aus mindstens zwei Zellen zusam- 

 men gesetzt ist, von denen die eine den Driisenantheil derselben, die 

 andere den Central- und Spiralfaden bildet, welche Beide ja eigentlich 

 nur einen einzigen Faden vorstellen" ('92, p. 102). Schneider is of 

 opinion that, before the differentiation of the mother cell of the colloblast, 

 the nucleus is multiplied by repeating division, until seven nuclei are 

 formed in the same cell at last. One of these nuclei occupies the 

 position at one end of the cell, where the cytoplasm has been in the 

 mean time filled with yellowish refringent granules, Schneider calls this 

 part of the cell the granular cell (" Kornerzelle "). The other part of 

 the cell is split longitudinally into six portions named the fibrous cells 

 (" P^aserzellen "), in each of which one of the remaining six nuclei is 

 enclosed. All the fibrous cells are elongated in the longitudinal direction. 

 The granular cell is also divided longitudinally into six portions, and each 

 of them is connected with a fibrous cell. Each portion of the granular 

 cell develops into the head of the colloblast, and each fibrous cell into 

 the spiral filament. Thus, according to Schneider's opinion, a single 

 mother cell should give rise to six colloblasts. 



Abbott's observation conforms nearly with mine as to the origins 

 of the head and spiral filaments, but not on the development of the 

 central filament as well as of the spheroidal body in the head. As to 

 the central filament, he describes that the filament is " derived from the 

 denser cytoplasm immediately surrounding the nucleus". And regarding 

 the spheroidal body, he seems to be of the opinion that the body is 

 derived from the nucleus of the mother cell, as it is previously remarked. 

 However, it is certain that the spiral filament, as well as the spheroidal 

 body, develops from the cytoplasm of the mother cell, and the central 

 filament from the nucleus. The difference of staining reaction shows 

 this most unm.istakably, without mentioning other differences of minor 



