THE PRESENT POSITION OF CELL-THEORY. 97 



the cell-theory, and do not the words which he used with 

 regard to the union of elementary atoms to form atoms of 

 the second order show a prescience of the assumptions 

 which would have to be made to explain the powers mani- 

 fested by cells ? Because he confined himself to the one 

 question, it is not fair to say that Schwann had not a clear 

 appreciation of the importance of the other. I may relate, 

 in this connection, an anecdote which will finally clear 

 Schwann's reputation from the reproach fastened upon it. 

 Professor Lankester tells me that about the time when a 

 sort of jubilee was held in Schwann's honour at Liege in 

 1878, he was introduced to him, and ventured to ask in 

 the course of conversation how it was that after the publica- 

 tion of his famous essay he had so long been silent. 

 Schwann answered that he had not been idle, but that 

 ever since he had been unsuccessfully occupied in trying to 

 find out the secret of the constitution of the cell. 



To return to the question propounded by Schwann, 

 does the cause of organic phenomena lie in the organism or 

 in its separate elementary parts, the cells ? He answers 

 very decidedly, in the separate elementary parts, and gives 

 the following reasons for his answer: " All organised 

 bodies are composed of essentially similar parts, namely, of 

 cells ; these cells are formed and grow in accordance with 

 essentially similar laws, and therefore these processes must 

 in every instance be produced by the same powers. Now 

 if we find that some of these elementary parts not differing 

 from the others are capable of separating themselves from 

 the organism and pursuing an independent growth, we may 

 thence conclude that each of the other elementary parts — 

 each cell — is already possessed of the power to take up fresh 

 molecules and grow, and that therefore each elementary 

 part possesses a power of its own, an independent life, by 

 means of which it would be enabled to develop itself in- 

 dependently if the relations which it bore to external parts 

 were but similar to those in which it stands in the organism. 

 The ova of animals afford us examples of such independent 

 cells apart from the organism." 



A little further on he says : " In inferior plants any given 



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