DEFENSIVE FERMENTS OF THE ANIMAL ORGANISM 13 



compounds, from the elements of which the body 

 cells may construct their own material, or else renew 

 their supply of energy. In the latter case, too, as 

 has been mentioned before, a preparatory decom- 

 position (a kind of adaptation to the cell) is necessary. 



An analogy may be used to make clear this kind 

 of reconstruction. Suppose an architect is called 

 upon to convert a certain building, which has been 

 specially designed for a particular purpose, into one 

 suitable for an entirely different object. He would 

 only be able to carry out this work on the condition 

 that he might pull down the original structure. He 

 would naturally be able to work some of the bricks 

 of the old building into the plans of his new one. 

 Some of the bricks, or even combinations of bricks, 

 may be used as they are, others will have to be recut, 

 while others, again, are of no value whatever. In 

 just the same w^ay does the animal organism act 

 towards the specifically constructed parts of the cells 

 which are used as food. First of all comes the dis- 

 integration into simple compounds, and then a recon- 

 struction, according to entirely new plans, on the 

 other side of the intestines. 



The simplest conditions, in this respect, are to be 

 seen amongst mammals during the suckling period, 

 when, under normal conditions, the animal imbibes 

 the milk peculiar to its species. This, as G. von 

 Bunge first demonstrated very precisely, is in every 



