22 CHARLES F. W. MCCLURE, 



nehmen die Neuroglia-Fbrillen ein dichteres Gefüge an unter gleich- 

 zeitiger Vermehrung ihrer Kerne und gehen nach innen continuirlich 

 in das grobfibrilläre Ganglien zell-Spongioplasma über, entweder am 

 Rand der Ganglienzelle oder tiefer in ihrem Innern, im letztern Fall 

 häufig unter Bildung von Bäumchen, welche besonders bei den Ganglien- 

 zellen mit heller Randzone scharf hervortreten (Holzschn. Alu. 2). 

 Aus diesen Beobachtungen folgerte ich, dass das Spongioplasma der 

 Ganglienzelle nur ein Stützgerüst darstellt und das eigentlich Nervöse 

 das von diesem umschlossene Hyaloplasma ist, welches an frischen, 

 unter schwachem Druck befindlichen Ganglienzellen in Gestalt grösserer 

 oder kleinerer glasheller Tropfen austritt." 



He further states that in addition to the coarse fibrils the neuro- 

 glia tissue is also made up of fine fibrils, which in structure resemble 

 those found in the nerve cells. On account of this close resemblance 

 which exists between the fibrils of the nerve cells and those of the 

 neuroglia, he concludes that the former must possess the same functions 

 as the latter (Stützgerüst). 



In the following pages I hope to be able to disprove the exi- 

 stence of coarse neuroglia fibrils in the nerve cells of Gastropods. 

 Rohde's last paper (38) which deals with the development and growth 

 of nerve cells will be considered further on in connection with another 

 topic. 



Haller (13 and 14), in a manner similar to Kupffer, divides 

 the cell substance into "Proto- and Paraplasma". The former is 

 arranged in the form of short fibrils which distribute themselves in 

 the "Paraplasma" according to the functional status of the cell. Thus 

 any functional change in the cell may produce a correspondingly 

 different arrangement of its elements. For example — under certain 

 conditions, the fibrils may have an irregular distribution, or they may 

 be concentrically arranged in the cell body ; they may be so regularly 

 distributed, that in sections they will appear as coarse or fine granules ; 

 or finally, they may be so distributed in the cell, as to produce the 

 appearance of a network. 



BiNET (1) speaks of the difficulty experienced by him in pro- 

 curing good sections of nervous tissue from certain Invertebrates, and 

 ascribes his inability to do so, as due to the circumstance that these 

 tissues are enclosed by dense layers of connective tissue which prevent 

 the entrance of the fixing fluid. 



The writer also experienced, at first, a similar difficulty in 

 procuring good sections of the nerve cells of Crustaceans and worms 



