The Unity of the Organism 



A True Nervous System Probably Present in Some Protozoa 



Should further investigations confirm these discoveries, as 

 one may predict they will, nothing but purely speculative 

 considerations can restrain comparative anatomists from 

 putting the nervous system of the Diplodinium type along- 

 side that of some worms, so far as structural elaborateness 

 and functional effectiveness are concerned. Of course there 

 can be no possibility of homology between the two types, 

 if the term homology be used with the meaning generally at- 

 tached to it in comparative morphology. 



If the possession by a protozoan of a nervous system 

 thus elaborate should be fully established, the fact would 

 have far-reaching consequences on our theories about these 

 animals. A few remarks are therefore in order as to the 

 probable general correctness of Sharp's observations. In 

 the first place, Mr. Sharp's statement, "Whatever there may 

 be of merit in the methods used and the results so far ob- 

 tained, is due to the kindly and helpful suggestions and in- 

 terest of Professor Kofoid, under whose direction the work 

 has been done," 18 should be noticed. It may be taken for 

 granted, I presume, that Professor Kofoid's wide knowledge 

 of the protista, and his long experience in the technique of 

 such research as that here involved constitute a weighty 

 guarantee for the trustworthiness of the results. The gen- 

 eral "internal evidence" of carefulness, for which well-prac- 

 ticed biologists come to have so keen an eye, will, I think, 

 be recognized by all who read Mr. Sharp's memoir. From 

 the morphological side, the point most open to question is 

 that of the trustworthiness of the differential action of the 

 stains used. A modification of Mallory's connective tissue 

 stain seems to have been Sharp's main reliance, and it is 

 unfortunate that he does not inform us how this affects fib- 

 ers positively known to be nervous. Furthermore, it must 

 be remarked that the seeming identity of staining of this 



