60 DR. HUGHES BENNETT 



become aggregated together, or coalesce to form larger 

 masses. Under no circumstances known do living particles 

 become aggregated to form a compound living mass, but 

 each absorbs nutrient matter and divides into smaller 

 masses. Indeed living particles multiply in number, ema- 

 nating from, instead of collecting towards, centres. 



Before inanimate substances can become living they 

 must be reduced to the state of solution, and there is 

 reason to believe that at the moment when the matter 

 becomes endowed with vital properties the relation of its 

 component elements to each other becomes totally altered. 

 These elements being afterwards arranged in obedience to 

 powers resident in the living matter, in such a manner as to 

 give rise to the production of certain definite compounds, 

 but as these compounds are formed, the material ceases to 

 exhibit those endowments to which, it seems to me, the 

 term vital should be restricted. (See Part III.) 



It has been shown that the outermost part of the 

 so-called " cell-wall " is the oldest portion of the structure, 

 and that it is increased in thickness from within. Hence, 

 according to Dr. Bennett's view, we must suppose that two 

 distinct processes take part in the formation of this struc- 

 ture, (i) Matter from the surrounding medium being first 

 deposited over the surface of the mass, while (2) this is 

 afterwards thickened, not by the addition of new layers upon 

 the external surface, but by matter which is deposited from 

 within. It seems very unlikely that the outer layer should 

 be formed in one way and the inner layers in a very different 

 way, for very often the several layers are alike, and continuous 

 in structure one with the other; no line of demarcation exists, 

 and no difference whatever can be demonstrated. 



