66 THE TISSUES. 



prematurely as free spherical corpuscles, usually larger than 

 leukocytes. 



Emulsions : Milk and chyle are emulsions, as are also the 

 yolk of birds' eggs and the milky juice of certain plants. By 

 means of certain substances, as albumin, oil may be caused to 

 form a permanent mixture, or emulsion, with water. The oil 

 forms minute spherules or granules enveloped in a viscid sub- 

 stance, which causes them to retain their shape, and suspended 

 in the watery vehicle. Milk and chyle contain large numbers 

 of such fat-granules, which are very minute and are sus- 

 pended in an abundant aqueous fluid. Their opacity and 

 whiteness are due to the reflection of the rays of light from 

 the granules. In artificial emulsions the spherules of fat are 

 much coarser and the proportion of water that can be intro- 

 duced far less than is the case with these natural emulsions. 



