ON THE VITALISTIC VIEW OF NATURE. 371 



Schwann defined the cell as " a small vesicle with a 

 firm membrane enclosing fluid content." l But the 

 cellular theory was gradually replaced by the proto- 

 plasmic theory of Max Schultze, the distinct membrane 

 was found to be frequently absent, and there only 

 remained "a small mass of protoplasm endowed with 

 the attributes of life." The cell, which had once been 

 compared to a crystal, became a very complicated and 

 indefinite thing : it became, in the conception of 

 biologists, an " organism." 2 Further, the nucleus or 

 kernel to which Schleiden attached great importance 

 in his cellular theory was, for a while, quite lost sight 

 of it being for a long time held that there exist non- 

 nucleated cells. Elaborate theories, such as that of 

 Haeckel, 3 were founded upon this view, till in more 



1 O. Hertwig, ' The Cell,' p. 5 n. 



- Treatises on the subject now 

 usually begin with an apology, the 

 word cell being considered mislead- 

 ing. Thus Hertwig says ((oc. cit., 

 p. 8), " It is evident that the term 

 * cell ' is incorrect. That it has, 

 nevertheless, been retained may be 

 partly ascribed to a kind of loyalty 

 to the vigorous combatants who 

 conquered the whole field of his- 

 tology under the banner of the 

 cell-theory, and partly to the cir- 

 cumstance that the discoveries 

 which brought about the new 

 reform were only made by degrees, 

 and were not generally accepted at 

 a time when, in consequence of its 

 having been used for several de- 

 cades, the word cell had taken 

 firm root in the literature of the 

 subject." 



3 " Since, in consequence of the 

 inadequacy of former methods, no 

 nuclei had been discovered in many 

 of the lower organisms, the exist- 

 ence of two kinds of elementary 



cells was assumed more simple 

 ones, consisting only of a mass of 

 protoplasm, and more complex ones, 

 which had developed in their in- 

 terior a special organ, the nucleus. 

 The former were called cytodes by 

 Haeckel (1866), to the simplest 

 solitary forms of which he gave the 

 name of Monera ; the latter he 

 called celluUc, or cytes. But since 

 then the aspect of the question 

 has been considerably changed. 

 Thanks to the improvements in 

 optical instruments and in staining 

 methods, the existence of organisms 

 without nuclei is now much ques- 

 tioned." (Hertwig, 'The Cell,' p. 

 54. See also Hiicker, p. 239.) On 

 the other side M. Delage says 

 (' L'He're'dite,' p. 37), " Apres avoir 

 ddcouvert un noyau chez la plupart 

 des inoneres et des cytodes et 

 meme chez les BacteYies, on a, par 

 une induction h, mon sens un peu 

 hative, ni<5 1'existence d'organismes 

 sans noyau." 



