Attempt to Subordinate Protista to Cell-Theory 285 



knowledge favors the former and tends to refute the latter; 

 and in so far as Ehrenberg stood for the former and Du- 

 jardin for the latter the evidence surely supports the views 

 of the German and opposes tliose of the Frenchman. 



This brings us to a highly important practical point. I 

 mentioned a little while ago that Dujardin's theoretical 

 views influenced harmfully his observational work. In sup- 

 port of this statement the reader is asked to compare the 

 monographs by Ehrenberg and Dujardin already mentioned, 

 giving special attention to figures of the same animal pre- 

 sented in each. No one will fail, I believe, to recognize the 

 greater truthfulness (disregarding the relative merit of 

 draftmanship and publication) of many of Ehrenberg's il- 

 lustrations, especially as regards the internal stinjcture of 

 the organisms. That tlie diff'erence cannot be attributed 

 altogether to Ehrenberg's superior powers of observation 

 seems certain from the fact that Dujardin made out numer- 

 ous points about the cilia of various species which were un- 

 known to Ehrenberg. Both Dujardin's observations and his 

 scheme of classification appear to have been largely influ- 

 enced by his sarcode theory: i.e., his theory of structureless- 

 ness. "The numerous genera which one establishes," he 

 says, "in the family of the monadinians, are distinguished 

 therefore only by the number and position of the locomotor 

 filaments and by the most habitual form of the body and of 

 the appendages." ^ 



Prepossessed by the idea of structural diversity and com- 

 plication in the creatures of the microscopic world, Ehren- 

 berg directed his attention primarily to their internal make- 

 up, described things that do not exist there, and overlooked 

 various external parts. Dujardin, on the other hand, pre- 

 possessed by the idea of internal structurelessness, of homo- 

 geneity, fixed his attention more on the external parts and so 

 was able to surpass Ehrenberg in describing these, but also 

 to correct various of his opponent's erroneous interpi*eta- 



