CHEMICAL PHENOMENA IN LIFE 



in diameter. We call particles of and above this 

 size Microns. The ultramicroscope makes par- 

 ticles visible even down to the size of 6 /*/*, provided 

 that the power of light applied is strong enough. 

 Such particles are called Submicrons. But in 

 solutions of albumin or of starch-paste even the 

 ultramicroscope does not dissolve the cone of 

 light into single particles. Nevertheless, it is 

 highly probable that even in such solutions 

 separate particles exist which are smaller than 

 6 /M/A. Such are called Amicrons. The presence of 

 amicrons can be shown indirectly, for such 

 corpuscules readily become the nuclei of pre- 

 cipitates. When amicrons are present, precipita- 

 tion is more easily effected than without them. 

 The size of 6 //,/x in diameter is probably the size 

 of the albumin molecules themselves. Thus by 

 means of the ultramicroscope it has been made 

 possible to distinguish the largest molecules of 

 colloidal substances and to demonstrate the 

 reality of existence for the molecules. Submicrons, 

 however, are generally already aggregations of 

 molecules. In such a way we can get at least a 

 glimpse of the molecular structure of colloids, 

 and of protoplasm in particular. Protoplasm, 

 in the same way as colloidal solutions, must 

 generally be considered as a heterogeneous system. 

 Solid particles of different colloidal substances are 

 suspended in a liquid. The particles are of 

 different sizes. Some do not differ in size from 

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