THE CELL-THEORY 26 1 



The endoplasts grow and divide, the periplast grows so as to surround 

 the endoplasts completely, and except so far as its tendency is, to fill 

 up the space left by their separation, there is no evidence that its 

 growth is in any way affected by them, still less, that it is, as is often 

 assumed, deposited by them. We are led, then, to the conclusion that 

 though Schwann's great principle of the identity of structure of plants 

 and animals is perfectly correct, his exposition of it is incorrect, ' 

 inasmuch as the corpuscle of cartilage (his " nucleus," whence he 

 reasoned to the other " nuclei ") answers not to the " nucleus," but to 

 the " primordial utricle " of the plant ; since the mode of development 

 of new " cells," though identical in each case, is different from what 

 Schleiden stated, and Schwann believed ; and, finally, since, for the 

 notion of the anatomical independence of the cells, we must substitute 

 that of the unity and continuity of the periplastic substance in each case. 



Intimately connected with these structural errors, as we cannot but 

 think them, are Schwann's views of the nature and powers of the 

 " cell," and those subsequently developed (principally by Kolliker) 

 with respect to the action of the nuclei as " centres of force." Led 

 apparently by his views of its anatomical independence, Schwann 

 maintains, as a general proposition, that the cell as such possesses 

 powers which are not inherent in its separate molecules. — -^ 



" We must, in fact, ascribe an independent life to cells — i.e., the 

 combination of molecules which take place in a single cell are sufficient 

 to set free the force, in consequence of which the cell has the power , ^ 



of attracting new molecules. The cause of nutrition and growth lies Ay . , 

 not in the organism as a whole, but in the separate elementary parts — J j' 

 the cells. That in point of fact every cell, when separated from the ^ ^ 

 organism, is not capable of further growth as little militates against 

 this theory, as its incapability of existing separate from the swarm 



would be an argument against the independent life of a bee 



The inquiry into the fundamental forces of organisms, therefore, is 

 reduced into one concerning the fundamental forces of the single cells." K 

 (p. 229.) 



And yet, strongly as Schwa nn maintains, not on ly her e but in many 

 other places, the view that the vital forces are manifested _bY_the_cells 

 as machines, and are not inherent in the matter of which these cells 

 are composeg',"apart from tlieiF"torm ; h e gives it u p in eff ect when he 

 comes to treafoTThese torce sTrTdetail . The fundamental cell-forces 

 are, he says, o?' two kihdsTTRe attractive and the metabolic, the former 

 regulating growth, the latter determining the chemical changes ; and 

 he shows very justly that these forces are not located in any special 

 centres in the cell, but are exhibited by all its solid constituents (pp. 



