ON THE VITALISING VIEW OF NATURE. 443 



The modern theories of the cell, of metabolism, and 

 selection, have also greatly influenced and modified our 

 conceptions concerning the last and most important pro- 

 perty of all living matter viz., that it is self- reproductive. 

 Older text -books on physiology treated of the great 43. 



Reproduc- 



problem of generation i.e., the origin of a new individual tion. 

 as a phenomenon of organised life which stood quite 

 isolated; and although the sexual difference in plants 

 and animals had early led to certain analogies, to similar 

 terminology, and to vague inferences, the mysterious 

 phenomena of generation, and especially of sexual genera- 

 tion, were not brought into line with the general pro- 

 perties of all living matter till about fifty years ago. 

 Even Johannes Miiller in his great text - book on 

 Physiology, which takes a much wider view of the sub- 

 ject than any work before it, treats of the reproduction 

 of tissues and of generation in quite separate, seem- 

 ingly disconnected, parts of his work. Into this un- 

 certainty only little light was thrown by the original 

 propounded of the Cellular theory, who, misled by the 

 supposed analogy of cells and crystals, imagined that 

 cells originated out of the surrounding cell sap, as 

 crystals solidify out of the solution or mother liquor. 

 Corrector views were gradually elaborated by botanists. 

 Mohl emphasised the important part which protoplasm 

 plays in the formation of cells. Nageli established the 

 process of intussusception as against external accretion ; 

 anatomists like Max Schulze and Briicke joined hands, 



possible express the doctrine which which, being interpreted, means 

 Dr Gaskell and Prof. Hering have winding-up, and ' catabolism,' run- 

 embodied in words which have now f niiig down are the creation of Dr 

 become familiar to every student. Gaekell." 

 The words in question ' anabolism,' 



