SCHWARZ >S VIEWS 207 



became vacuolated," seems to me to go too far, and to be in 

 the main unfounded, since in any case there certainly could 

 be no question of precipitates within the cell sap. 



Finally, we must mention further, that van Beneden 

 (1883) also convinced himself that the most important of 

 the structures described by him in the sexual products of 

 Ascaris were to be observed while still in the living condition. 



In Protozoa, which are especially important for the 

 structure of living protoplasm, Biitschli (1887), Fabre 

 (1887), Schewiakoff (1889), and others, have traced the 

 living structures. 



Taking into consideration all that has been enumerated, 

 which could certainly be further increased by a more 

 conscientious search through the literature, as well as, 

 on the other hand, the further proofs which I have com- 

 municated in this work, it may well be asserted that the 

 structures in question are frequently to be observed quite 

 plainly in the living condition, and therefore cannot be 

 any 'artificially produced appearances of precipitation or 

 coagulation. 



Now Schwarz allows reticular or filamentous structures, 

 which can be precipitated or fixed, in the case of the nuclei 

 and chlorophyll bodies, but denies them, on the other hand, 

 in the case of protoplasm ; and why ? He asserts, in fact, 

 that in the fixed framework of the protoplasm, a chemical 

 difference between the framework and its contents is not 

 demonstrable. The contents of the meshes stain in the same 

 manner as the meshes, and therefore also consist of a 

 coagulable substance. The difference between the frame- 

 work and its contents only consists in a slight difference 

 of density ; both are said to consist of plastin. The 

 contents of the meshes is said not to be a fluid (p. 

 131); this contrasts very strongly with the descrip- 

 tion given on p. 140 of the same framework in fixed 

 protoplasm, where it is stated " the cavities " (i.e. those of 

 the framework) "are for the most part filled with fluid, but 

 may, under certain circumstances, also be filled with a less 

 dense substance." I must say I think Schwarz would find 

 few to agree with his view of the chemical similarity between 



