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TII£ BEGINNINGS OF LIFE. 



303 



since Mr. Rainey's discovery that crystals are produced 

 much more slowly, and undergo very important modi- 

 fications in shape, when they are formed in viscid 

 solutions, the formation of these bodies has, in both 

 respects, become much more obviously comparable with 

 that of organisms. The appearance of these modified 

 crystals may be best watched after mixing solutions 

 of gum and carbonate of potash in the manner which 

 has been carefully described by Mr. Rainey. Owing 

 to the viscid properties of gum, a solution of this sub- 

 stance diffuses with difficulty, and hence, when brought 

 into contact with a solution of carbonate of potash, the 

 malate of lime of the gum only decomposes very slowly. 

 The insoluble carbonate of lime, instead of appearing in 

 its usual crystalline condition, is precipitated in the form 

 of globules resembling calculi. Mr. Rainey thus describes 

 what takes place when portions of the two solutions 

 are mixed under the microscope: — ^The appearance 

 which is first visible is a faint nebulosity at the line of 

 union of the two solutions, showing that the particles 

 of carbonate of lime, when they first come into existence, 

 are too minute to admit of being distinguished indivi- 



microscop 



In a few hours 



exquisitely minute spherules, too small to allow of 

 accurate measurement, can be seen in the nebulous 

 part, a portion of which has disappeared, and is replaced 

 by these spherical particles. Examined at a later period. 



^ Mr. Rainey generally made use of one of Ross's ^' object-glasses. 



