72 THE PROTEOMORPHIC THEORY AND THE NEW MEDICINE 



contain the centers of cardiac and respiratory control, as do the 

 nervous centers. 



Considered in this broad way, there is ample justification for 

 the belief that the physiological activities of all drugs are inti- 

 mately linked with their chemical composition ; and that, in the 

 sense just interpreted, drugs of closely similar chemical compo- 

 sition have strictly analogous effects. 



But everything depends upon the particular tissue cell which 

 chances to have affinity for any given drug ; and the experiments 

 of Abderhalden as already cited, showing the elective affinities 

 of different tissues for polypeptids, may be considered as labora- 

 tory interpretations of familiar facts of clinical medicine. The 

 fact that many alkaloids and such poisons as that of B. tetanus, 

 and, indeed most of the, bacterial toxins, give evidence of affecting 

 the brain, dove-tails, at least presumptively, with the highly inter- 

 esting experiments that show that two of the most complex of 

 the polypeptids were hydrolyzed by the juices expressed from 

 the brain cells of a calf. 



It may be added that in the case of two less complex types of 

 polypeptids, the juices of the calf-brain failed to act; and con- 

 ceivably it is not stretching analogies too far if we observe that 

 the alkaloids which are known to have a pronounced cerebral effect 

 are considerably more complex, particularly as regards their car- 

 bon and hydrogen atoms, than the simpler (di-amino) polypep- 

 tids; and if we associate relative complexity of molecular struc- 

 ture in a drug with affinity for the cerebral tissue, in itself 

 presumably the most complex of organic bodies. 

 . Such a conception must be held with great reserve, however, 

 in view of the extraordinary toxicity of the simple combinations 

 CS 2 , carbon bisulphide, and HNC, prussic acid, and of the con- 

 flicting evidence elicited by observation that, whereas nitriles of 

 the fatty series, from acetonitrile to isovaleronitrile, increase in 

 toxicity with growing molecular weight, substances of an allied 

 series, starting with cyanacetic methyl ester, C 4 H B HO 2 , become 

 less toxic (according to Berthe and Ferre) with increased com- 

 plexity, losing toxicity altogether when two groups of C 2 H 5 O 2 are 

 inserted. A clue will perhaps be found in the study of the 

 valencies of the nitrogen atom, which, as is familiarly known, 

 is either trivalent or quinquevalent. 



SPECIFIC AFFINITIES AND ANTAGONISMS 



Closely in keeping with these rather abstruse theoretical con- 

 siderations are the familiar and very practical experiments of 

 Pasteur through which the anti-rabic virus was developed. Here, 

 as is well known, the material used for making the protective 



