52 Transactions of the 



are led in the direction long since indicated by Mr. Eainey to 

 extend our notions of the functions performed by the chemical and 

 physical forces at work, according to their own methods, in living 

 things. The action of the silica in the cases cited seems to be 

 chiefly physical and mechanical, but the appearance of the crystals, 

 especially when viewed under considerable magnification, leads to 

 the belief that some portion of the silica is present in them and 

 not eliminated as the process of crystallization goes on. Other 

 methods have been long practised by microscopists to modify crystal- 

 lization, and which appear to depend upon the same principle of 

 offering resistance to the normal action of crystalline force. One 

 advantage of employing silica, as described, is that we can obtain a 

 number of interesting patterns with films of that substance alone, 

 and compare them with the varieties of crystalline patterns obtained 

 from simple aqueous solution, and with those producible from the 

 mixed solutions. Fellows of the Society experimenting in these 

 directions, will do well to examine the beautiful slides of various 

 crystals prepared by Mr. Norman, which will be found in the 

 Society's cabinet. 



