ALLEGED OCCURRENCE OF FIBRILS 181 



obtains the appearance of isolated filaments in a granular 

 matrix. 1 



The same objections which I have just raised against 

 Flemmiug's view of the fibrillar structure of protoplasm, 

 must of course also apply to the corresponding descriptions 

 of earlier and later investigators. For ganglion cells H. 

 Schultze (1878) and Kohde (1887) declared themselves of 

 this opinion. In the same way Pfeffer (1886) and Pfluger 

 (1889) have assumed the fibrillar structure, without, how- 

 ever, having brought forward any investigations of their 

 own upon this point. Pfluger especially expressed himself 

 very plainly. The gelatinous condition of the cell contents 

 represents according to him "a mixture of an absolutely 

 fluid with an absolutely solid material." The solid substance 

 is supposed to be partly granular, and partly, on the contrary, 

 at any rate in its chief mass, a feltwork of very minute 

 filaments (p. 30). 



Of a similar opinion is Ballowitz (1884), who in like 

 manner believes protoplasm to consist of interwoven, con- 

 tractile filaments, which are not, however, connected together, 

 while Eabl (1889) adopts this conception to the extent 

 of assuming the presence of isolated fibrils at certain 

 times at least, especially during the division of the cells, 

 when they appear in the form of radiating systems. In the 



1 In his most recent work (1891, Archiv. f. mikroskop. AnaL, Bd. xxxvii. 

 p. 736) Flemming expresses himself as follows upon protoplasmic structures : 

 " I am one of those who, reasoning from visible phenomena, assume a real 

 formed structure in the cell, even though it may not be fixed or permanent, 

 and who cannot agree with the opinion that the cell is an emulsion, and the 

 fibres that can be made out in it only the expression of streaming movements." 

 A more detailed discussion of this casual expression of opinion, in so far as it 

 would have reference to my conceptions, seems to me unnecessary, since the 

 whole of the present work may be taken as a fundamental contradiction of it. 

 Only the uncertainty of such expressions as " formed structure," which "is 

 not fixed or permanent," may here be pointed out. I hope that Flemming 

 will convince himself in these matters also of the correctness of my views in 

 principle, just as he has with regard to the question of nuclear division. I 

 must not omit to point out the fact that he frequently speaks of reticular 

 fibres in protoplasm in the work cited, but in his figures he depicts tangles 

 of undulating fibrillfe without distinct net-like connections, just as he has 

 usually done. That this in no way corresponds to the reality is sufficiently 

 obvious already from the investigations of my predecessors. 



