The Organism and its Protoplasm 129 



meaning that he conceived protoplasm to be essentially dif- 

 ferent in different organisms as concerns some of its at- 

 tributes. For example, after speaking of the differences 

 he had observed in two species of rhizopods of the same 

 genus, Gromia ovtfornm and (j. Dujardinia, he says, "I 

 bring this forward only in order to point out in indubitable 

 cases of naked protoplasm differences again in movement, 

 consistency, and tendency to fuse with like substances with 

 which it conies into contact, upon which differences we come 

 again in the naked cells of the tissues of higher animals." 

 The immediate point Schultze was aiming to establish here 

 was the individuality, in the sense of preservation of iden- 

 tity, of the protoplasmic mass which he was contending to be 

 the essential thing in the cell, without the presence of a 

 membrane or any sort of limiting outer layer to insure that 

 individuality; so it is only secondarily that his argument 

 touches upon the attributes of differentiation of the proto- 

 plasm itself as between different cells. Nevertheless his in- 

 sistence in several connections on the differences, particu- 

 larly in consistency and resistance of the protoplasm, surely 

 bears strongly in this direction. I believe, then, enough has 

 been said to show that the conception of protoplasm held 

 by the "father of modern biology" gives no warrant for the 

 Huxlevan and more recent conception of the essential iden- 

 tity of the protoplasm in all organic beings. 



Ernst Brilckc's Conception of the CeU as a/n Organism 



Another essay recognized as constituting part of the 

 classical literature of modern biology is Ernst Brucke's 

 "Die Elementarorganismen." This essay is likewise particu- 

 larly important for our enterprise, though in a considerably 

 different way from the one just examined. Although 

 Brucke's labors lay so largely in the same field with those 

 of Schultze, and although he was familiar with his con- 



