THE IXADEQi'ACY OF THE CELL-TH I-IORV. 



I I 



time, but smaller individuals, as no growth was possible. 

 The experiment reminds one of the half- or quarter-sized 

 embryos obtained by separating the first two or ionr blasto- 

 meres. 



Grubcr's highly interesting paper calls attention to the iden- 

 tity in form and structural detail of the "membranellae " of 

 Stentor with the so-called "corner-cells" (Eckzellen) of mol- 

 luscs {Cj'c/as cornea). The comparison is a most instructive 

 one, illustrating in the most conclusive manner that differenti- 

 ation of the parts of the soma depends, not on the interaction 

 of cells, but upon the elementary structure of the protoplasm. 



Fig. 2. — A, three membranellae of Stentor, B, membranella in section. 

 C, Section at the base of the two plates. Bl, Basal lamella. Ef, Terminal fibre. 

 Bf, Basal fibril. K, Nucleus. 



The membranellae of the frontal field of Stentor consist of two 

 thin, adherent plates, each of which represents a number of 

 coalesced cilia. The structure has a basal seam or ridge ^ 

 (Leiste), and a basal lamella which is continued into a termi- 

 nal fibre. All these fibres are connected by the basal fibril, 

 throuo-h which the movements of the membranellae are evi- 

 dently regulated. 



Now this highlv differentiated organ, the membranella, is 

 reproduced with most remarkable exactness in the " corner- 

 cell " of Cyclas. But here the organ represents an individual 



^ This seam consists of a series of microsomes, as Dr. Watase has discovered. 



