THEORY OF THE CELLS. 213 
even the premises which have been set forth have in all points 
the requisite force. or too little is still known of the cause 
of crystallization to predict with safety (as was attempted above) 
what would follow if a substance capable of imbibition were to 
crystallize. And if these premises were allowed, there are two 
other points which must be proved in order to establish the 
proposition in question: 1. That the metabolic phenomena of 
the cells, which have not been referred to in the foregoing 
argument, are as much the necessary consequence of the faculty 
of imbibition, or of some other peculiarity of the substance of 
cells, as the plastic phenomena are. 2. That if a number of 
crystals capable of imbibition are formed, they must combine 
according to certain laws so as to form a systematic whole, 
similar to an organism. Both these points must be clearly 
proved, in order to establish the truth of the foregoing view. 
But it is otherwise if this view be adduced merely as an hypo- 
thesis, which may serve as a guide for new investigations. In 
such case the inferences are sufficiently probable to justify 
such an hypothesis, if only the two points just mentioned can 
be shown to accord with it. 
With reference to the first of these points, it would certainly 
be impossible, in our ignorance as to the cause of chemical 
phenomena in general, to prove that a crystal capable of im- 
bibition must produce chemical changes in substances sur- 
rounding it; but then we could not infer, from the manner 
in which spongy platinum is formed, that it would act so 
peculiarly upon oxygen and hydrogen. But in order to 
render this view tenable as a possible hypothesis, it is only 
necessary to see that it may be a consequence. It cannot be 
denied that it may: there are several reasons for it, though 
they certainly are but weak, For imstance, since all cells 
possess this metabolic power, it is more likely to depend on a 
certain position of the molecules, which in all probability is 
essentially the same in all cells, than on the chemical com- 
bination of the molecules, which is very different in different 
cells. The presence, too, of different substances on the inner 
and the outer surface of the cell-membrane (see above, page 
199) in some measure implies that a certain direction of the 
axes of the atoms may be essential to the metabolic pheno- 
mena of the cells. I think, therefore, that the cause of the 
