THE PRESENT POSITION OF CELL-THEORY. 101 



Herbert Spencer followed with his theory of physiological 

 units. Darwin's theory of pangenesis expressed the same 

 idea, and more recently Nageli, De Vries, Wiesner, Weis- 

 mann and others have entered the same or at least similar 

 objections to the cell-theory. Even Oscar Hertwig, although 

 he appears in the sentence above quoted to give his 

 adherence to the view that the cell is a vital unit, abandons 

 this concept, for all practical purposes, in the latter part of 

 his book ; for he says, in a most unmistakable manner, 

 that the cell is an organism composed of ultimate units 

 which he calls idiosomes. 



Each author whose name I have quoted has a somewhat 

 different account to give of the ultimate constitution of the 

 cell. But the points on which they disagree are of subor- 

 dinate importance ; they are all agreed on the main issue, 

 that the vital activities manifested by the cell are not to be 

 explained by the visible constitution and structure of the 

 cell itself, nor by the mere chemical elements of which the 

 protoplasm of the cell is composed. Each of them avers 

 that the cell is organised, which means that it is made up of 

 countless organic units of a lower order, differing among 

 themselves, and arranged in groups and sub-groups within 

 the cell in a manner analogous to that in which the cells 

 themselves are arranged in a composite organism. Since 

 there is so general an agreement in fundamental principle, 

 1 am spared the necessity of examining each separate theory 

 of ultimate vital units in detail ; should anybody wish for a 

 condensed account of the various theories he will find it in 

 Weismann's introduction to his work on the Germ Plasm. 1 



structure d'un ordre plus eleve que la structure atomique des molecules 

 chimiques des composes organiques non vivants ". No fault can be found 

 with this definition, but would it not be better to adopt some other term to 

 express this extra complexity of structure rather than " organisation," which is 

 inseparably connected with our ideas of the composition of the bodies of 

 higher animals and plants? For Brucke the organisation of protoplasm 

 was the same in kind as the organisation of higher animals : for Dujardin 

 it was something different, and had best be expressed by a different term. 

 Delage puts the word structure in italics. 



1 Still better in Delage's book, referred to further on. 



