6o THE BEGINNINGS OF LIFE. 



potassic bichromate^. The cell-like compartments were 

 here much smaller than those of the substance described 



Fig. 39. 



Cellular Forms of Crystalline Matter, from a solution of Ammonic 

 Sulphate with Potassic Bichromate. ( X 800.) 



by Dr. Bennett, and each contained one or two unclear- 

 looking particles. The whole mass polarized light in 

 the most beautiful manner, and sank rapidly in water 

 when its upper surface was wetted. 



In addition to these modifications of crystalline form 

 under different conditions, there are still others whose 

 nature has been elucidated by Mr. Rainey. He has 

 shown that when carbonate of lime is slowly pre- 

 cipitated in viscid solutions of gum, albumen, or 

 even glycerine, the molecules of the nascent carbonate 

 unite with portions of the viscid ingredient, and 

 then — instead of arranging themselves into either 

 octahedral or hexagonal crystals — the combined parti- 



^ See vol. i. p. 451. 



