90 



THE BEGINNINGS OF LIFE. 



This tendency we must attribute to the large size 

 complexity of the colloidal molecules ^ Profi 

 Graham says on this subject : 



and 



essor 



Another and 



eminently 



characteristic quality of colloids is their mutability. 

 Their existence is a continued metastasis. A colloid 

 may be compared in this respect to water while existino- 

 liquid at a temperature under its usual freezing point 

 or to a supersaturated saline solution. ... * The solu- 

 tion of hydrated silicic acid^ for 

 obtained in a state of purity^ but it cannot be pre- 

 served. It may remain fluid for days or weeks in 

 a sealed tube^ but it is sure to gelatinize and become 

 insoluble at last* Nor does the change of this colloid 

 appear to stop at that point. For the mineral forms 

 of silicic acid deposited from water^ such as flinty are 



instance^ is easily 



r 



1 ' Applying to atoms the mechanical law which holds of masses, that 

 since inertia and gravity increase as the cubes of dimensions, while 

 cohesion increases as their squares, the self-sustaining power of a body 

 becomes relatively smaller as its bulk becomes greater ; it might be 

 argued that these large aggregate atoms which constitute organic sub- 

 stance, are mechanically weak— are less able than simpler atoms to 

 bear, without alteration, the forces falling on them. That very massive- 

 ness which renders them less mobile, enables the physical forces acting 

 on them more readily to change the relative positions of their com- 

 ponent atoms ; and so to produce what we know as rearrangements and 

 decompositions.' (Spencer, loc. cit. p. 14.) Professor Graham also 

 says :— ' It is difficult to avoid associating the inertness of colloids with 

 their high equivalents, particularly where the high number appears to 

 be attained by the repetition of a smaller number. The inquiry suggests 

 itself whether the colloid molecule may not be constituted by the group- 

 ing together of a number of smaller crystalloid molecules, and whether 

 the basis of colloidality may not really be this composite character 0/ 

 the molecule.' (Loc. cit. p. 221.) 



t 



/ 



\ 



?ra 



dual manr 



'for they alw^ 

 characteristic 



also be referi 

 materials wh 

 enter into th( 



But, let us 

 ments of thos 

 ance of Orga 



To all tho: 



' Even a ' coll 

 "lay be met wit! 

 Graham says :— ■ 

 gelatinous albuir 

 *^'» My facts mc 



"« no abrupt 

 absolute ? ' 



' ' ^^Tiile the . 

 P*^^^^ that nio 

 ;^^*^ from the 

 '"^"'^' that the . 



""^^ in wh; ? 



nd of, 



It 



