NEW CONCEPTIONS IN SCIENCE 



ably clear. On the basis of what is now known, 

 Professor Ehrlich, the distinguished head of the in- 

 stitute of experimental medicine at Frankfort, in 

 Germany, has constructed a theory which repre- 

 sents the very latest in this branch of scientific 

 work. Ehrlich supposes that, attached to the ex- 

 traordinarily complex structure of the animal cell 

 (a single cell may contain millions of atoms), there 

 exist what he terms "side-chains," or partly satu- 

 rated groups of atoms, whose normal function it is 

 to enable the cells to take up from the blood-stream 

 their food elements, which, passed on into the in- 

 terior, become a part of the cell itself. The con- 

 dition here is that the bond of momentary union 

 between the "side-chains" and the food elements 

 shall be easily formed and as lightly broken. These 

 side-chains he designates "receivers." 



Professor Ehrlich supposes the poisons to possess 

 a greater aptitude for fixing themselves to these 

 receivers, or, in chemical phraseology, to offer a 

 greater number of unsaturated affinities. Attach- 

 ing themselves to the receivers, they bar the way 

 to the entry of normal food materials, if, indeed, 

 they do not penetrate farther into the inner struct- 

 ure of the cell. In consequence, the activity of the 

 latter is disturbed ; death intervenes. 



Under certain conditions, however, the combina- 

 tion of side-chain and poison molecule is thrown 



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