1] MODIFICATION OF VITAL ACTIONS 17 



ONLY SLIGHTLY POISONOUS. VIOLENT POISONS. 



)CH - C 6 H 5 I /CH 



6 H 5 -CH = N/ C 6 H 5 -C = W 



- C 6 H 5 



hydrobenzamid. amarin. 



/CH = CH\ CH = CH\ 



CH/ I >H 



CH = CH X 



pyridin. pyrrol.* 



This increased poisonousness, correlated with the presence 

 of H joined to N, may be accounted for by the union of 

 this H with the O of the ketons or aldehydes of the living 

 substance. 



Likewise when one or more H atoms of the amido-group 

 are replaced by an acid radical (e.g. that of acetic acid, 

 CO . CH 3 ), the poisonous qualities of the substance are con- 

 siderably diminished ; thus, 



MORE POISONOUS. LESS POISONOUS. 



C 6 H 5 NH 2 CeHsNH . CO - CH 3 



anilin. antifebrin.t 



. NH 2 C 6 H 5 ira . NH . CO . CH 3 



phenylhydrazin. pyrodin. 



/NH 



HN = C( HN = C( 



.C0.^xx 2 



guanidin. dicyandiamidin. 



In like manner when, in an imido-group, the H (of the NH 

 radical) is replaced by alkyls (e.g. CH 3 ), the substances become 

 less poisonous ; thus, 



* While a 0.07 % solution of pyrrol kills Isopods, Rotifers, Planaria, etc., in 

 about 1 hour, these organisms withstand a solution of pyridin of the same 

 strength. (LoE\v, '87, p. 444.) 



t SCHURMAYER ('90, p. 445) finds that upon Ciliata (Carchesium) a 0.1% 

 solution slightly accelerates at first the action of the cilia, diminishes the rate of 

 succession of the phases of the contractile vacuole, and leaves the protoplasm 

 permanently more or less paralyzed, 

 c 



