CHEMICAL CHARACTERS OF CELL 79 



converted into the very substance of the cell 

 itself or into bye-products of one kind or 

 another. Of this production of bye-products 

 more must be said in a further paragraph, but 

 before passing to the general question, it may 

 be well, as we engaged upon the topic of 

 crystallisation, to point out that some living 

 organisms do construct crystals within them- 

 selves so that if the parallel between crystalli- 

 sation and assimilation were a fair one we 

 should be confronted with the somewhat 

 bizarre fact that one kind of crystallisation 

 was making use of another for its own 

 purposes. 



The facts, moreover, which have been brought 

 forward by Professor Minchin * show not only C 

 how different the two processes are but also 

 how the living cell is able to modify the process 

 of natural crystallisation for its own purposes. 

 He says : "An ordinary crystal owes its 

 peculiar characteristics entirely to the action of 

 the laws of inorganic matter, laws which admit 

 of being accurately formulated and accurately 

 calculated. Crystalline bodies are, however, 

 known to occur which have been deposited 

 within living bodies, and which owe their 

 origin to vital activities. In such cases, the 

 crystals, while identical in their chemical com- 



* " Living Crystals," Proc. Roy. Insl., vol. xv. 



