THE BEGINNINGS OF LIFE. 65 



the shapes of organisms (which are also compounded of 

 complex colloidal molecules) are in all probability solely 

 due to the properties of their molecules, as operated 

 upon by surrounding influences. There is, therefore, 

 a double approximate similarity of these aggregates 

 to organisms : first, on account of their molecular 

 mobility, and secondly, by reason of the forms which 

 they assume on emerging from the state of solution. 

 And both these characteristics are probably referrible to 

 the molecular complexity of their component units. 



If we now turn our attention to the solid aggregates 

 which may emerge from solutions of colloidal matter, 

 we shall find that they also are extremely variable in 

 nature, according to the ^ conditions' under which they 

 are formed. 



The starch-grains gradually deposited within the cells 

 of certain plants, present a structure which, in many 

 respects, closely resembles the calculi we have just 

 been describing. They, too, are produced slowly, and 

 apparently by a process of deposition within the tissue 

 of the plant; they frequently coalesce; they exhibit a 

 laminated structure; and they polarize in a very 

 characteristic manner. The transition from the calculi 

 previously described to starch-grains is, in fact, most 

 easy and natural, since Mr. Rainey has ascertained 

 that a certain amount of mineral matter, in the form 



by chemical analysis, and therefore, in its globular form it is obviously 

 an impure carbonate — a compound of this substance and gum or albu- 

 men.' (Loc. cit., pp. 35 and 31.) 



VOL. II. F 



