THEORIES OP IMMUNITY 180 



from these transformating reactions, and by utilizing other 

 substances the transformations of which furnish the energy 

 needed for the work so performed. 



An albuminous "micelle" thus may be compared to a 

 moving engine, which, thanks to special affinities, draws 

 from the medium through which it passes the fuel necessary 

 to produce its working energy, and at the same time matter 

 identical to its own in order to keep its parts in good repair 

 and even to strengthen them. 



Albuminous "micelles" are the nutritive units of living 

 matter, and all "micelles" of similar albumin have the same 

 physicochemical equilibrium. "Micelles" of different albu- 

 mins are distinguished among each other by differences in 

 physicochemical equilibrium and it has been determined 

 that the albumins of all beings belonging to the same plant or 

 animal species are the same. 



The albumins of different species have a different physico- 

 chemical equilibrium. Thus the white of egg from a hen 

 has not the same properties as the white of egg from other 

 birds, the casein of cow's milk is different from that of goat's 

 milk; the blood, the muscular or nervous substances of the 

 horse are different from the same substances fr,om all other 

 animals; whereas the salts and the crystalloids entering into 

 the composition of the tissues of different plants and animals 

 and which are derived from the albumins are always identical. 



The specific differences between the "micelles" and the 

 albumins which they form are therefore determined solely 

 by differences in the proportions of the component elements, 

 by the arrangement of these elements and by the different 

 physicochemical equilibria resulting. 



We do not know of any living being that might be con- 

 stituted by a single free albuminous "micelle." 



The biological unit of living matter is a cell, and a cell is 

 an arrangement of a certain number of albuminous "micelles" 

 of different structures, physicochemical equilibria and there- 

 fore functions which form a harmonious structural and 

 functional whole. 



At least three kinds of "micelles" can be distinguished in 

 a cell : those forming the plasma, the nucleus and the external 



