COMPOSITION OF SURROUNDING FL UID. 2 8 1 



core, and yet the resolution of complex matter into its 

 elements must take place, and the re-arrangement of these 

 in a new manner must occur in the central part of every 

 molecule of which every mass of living matters consists. 



As regards its chemical constitution, there can be no 

 doubt that the smallest particle of living matter is complex. 

 It is impossible to conceive the existence of a living particle 

 consisting of a simple substance only, as iron, oxygen, 

 nitrogen, &c. ; for living involves changes in which several 

 different elements take part. It appears to me that the 

 term living atom cannot with propriety be employed, because 

 living matter is of complex composition, while the idea of 

 an atom seems to involve simplicity of constitution, if not 

 indivisibility. 



Each spherical particle of living matter is free to move 

 in fluid, and the spaces which we must conclude exist 

 between the spherical particles of living matter are probably 

 occupied by fluid. This fluid contains, in solution, 



1. Matter about to become living ; 



2. Substances which exert a chemical action, but do 

 not necessarily form a constituent part of the living mass, 

 together with particles which are rejected, and not capable 

 of being animated by the particular form of living matter 

 present. 



3. Substances resulting from the changes ensuing in 

 particles which have arrived at the end of their period of 

 existence, and the compounds formed by the action of 

 oxygen upon these. 



Those who regard vital changes as purely physical, are 

 content to assure us that they are due to " molecular modi- 

 fications" brought about in some unknown manner, but they 



