BACTERIOLOGY IN A NUTSHELL. 



Physiological 

 Metabolism. 



Pathological 

 Metabolism. 



Immunitjr of 

 Some Animals 

 Explained. 



tween assimilable substances which serve for nutrition 

 and which enter into permanent union with the proto- 

 plasm and those which are foreign to the body. No 

 one believes that quinine and similar substances are 

 assimilated— that is — enter into the composition of 

 protoplasm. On the other hand, the food substances 

 are bound in the cells and this union must be considered 

 as chemical. One cannot extract a sugar residuum from 

 cells with water, but must first spht it oflf with acids in 

 order to set it free, but now such a chemical union 

 demands the presence of two binding groups of maximal 

 chemical afiinity which are suited one to the other. The 

 binding groups which reside in the cells and which bind 

 food substances I designate as "side-chains" or receptors, 

 while I have called the binding groups of the molecules 

 of food-stuffs the baptophores. I also assume that 

 protoplasm is endowed with a large series of such side- 

 chains or receptors, which through their chemical consti- 

 tution are able to biiid the diif erent food-stuffs and there- 

 by provide the prerequisite for cellular metabolism." 



This theory naturally applies to physiological 

 (constructive) metabolism. In pathological 

 (destructive), metabolism we have the presence 

 of an abnormal substance in the body juices 

 which forms new haptophores. According to 

 the "side-chain theory," the power of these 

 substances to exert injurious effects within the 

 body depends upon their ability to attach them- 

 selves to the cell receptors. In this way is 

 explained the immunity of some animals to 

 certain toxins, viz., — they lack the appropriate 

 receptors for the invading haptophores to com- 

 bine with. Should the invading haptophore 

 combine with a receptor, one of the following 

 phenomena takes place : 

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