BENNETT, ON THE MOLECULAR THEORY. 49 



tion. All these changes occur slowly, aud require time; but 

 their contemplation, Avhen regarded as purely physical phe- 

 nomena, must strike us Avith surprise, as being closely allied 

 to all our conceptions of the progress of life itself. 



Here the author explained that, in making use of the 

 expressions life and vital action, he was only using terms to 

 indicate phenomena which, in the present state of science, 

 cannot be accounted for by the ordinary laws of physics. 

 Or it might be said that certain actions are directed and 

 governed by conditions which are as yet undetermined, but 

 which, as they only occur in organic as distinguished from 

 inorganic bodies, constitute ^dtal actions. Not that an 

 organized body is independent of physical forces, but that 

 certain directions are communicated to them, which, as 

 invariably resulting in specific forms or properties, make up 

 the sum of what we call %dtality. 



Hence, although we see molecules combining in the 

 forms of crystals and nucleated spherules, inasmuch as we 

 have discovered the physical conditions on which they 

 depend, and can produce them artificially, we have no 

 difficulty in classifying these among purely physical phe- 

 nomena, even when they occur in the interior of animals. 

 But when other molecules unite to form nuclei, cells, and 

 fibres, and these arrange themselves into tissues and organs 

 to produce plants and animals, we are ignorant of the con- 

 ditions by which these results are brought about — Ave cannot 

 imitate them artificially, and are content to call them vital. 

 But the fact the author was anxious to point out Vv'as this, 

 that, so far as observation and research had enabled us to 

 investigate this difficult matter, it would appear that the 

 formations and disintegi'ations of vegetables and animals, 

 as Avell as the peculiar properties they exhibit, are essentially 

 connected with the molecular element. Thus, when Ave in- 

 vestigate the functions of plants and animals — for example, 

 generation, nutrition, secretion, motion, and sensation — we 

 find them all necessarily dependent on the permanent 

 existence and constant formation of molecules. 



Thus, generation, both in plants and animals, is accom- 

 plished by the union of certain molecular particles called the 

 male and female elements of reproduction. Among the 

 Protophyta the conjugation of two cells enables their 

 contents, or the endochrome, to mix together. This.endo- 

 chrome is a mass of coloured molecules, and the union of 

 two such masses constitutes the essential part of the genera- 

 tive act. In the Cryptogamia a vibratile, antheroid particle 

 enters a germ-cell, and finds this last filled with a mass of 



VOL. TI. NEW SER. r> 



