180 THE INDUCTIONS OF BIOLOGY. 



ing special units, which are ever present in them in large 

 quantities. The fluids circulating through the body contain 

 special units of this same order. And these diffused units 

 are continually being deposited along with the groups of like 

 units that already exist. How purely physical are the 

 causes of this selective assimilation, is, indeed, shown by the 

 fact that abnormal constituents of the blood are segregated 

 in the same way. The chalky deposits of gout beginning at 

 certain points, collect more and more around those points. 

 And similarly in numerous pustular diseases. Where 



the component units of an organ, or some of them, do not 

 exist as such in the circulating fluids, but are formed out of 

 elements or compounds that exist separately in the circulat- 

 ing fluids, the process of differential assimilation must be of 

 a more complex kind. Still, however, it seems not impossi- 

 ble that it is carried on in an analogous way. If there be an 

 aggregate of compound atoms, each of which contains the 

 constituents A, B, C; and if round this aggregate the con- 

 stituents A and B and C are diffused in uncombined states; 

 it may be suspected that the coercive force of these aggre- 

 gated compound atoms A, B, C, may not only bring into 

 union with themselves adjacent compound atoms A, B, C, but 

 may cause the adjacent constituents A and B and C to 

 unite into such compound atoms, and then aggregate with 

 the mass. 



