92 Physiological A ction of Nitrites of Paraffin Series. [June 1 6, 



member of the series of nitrites had to be contrasted with each of 

 the other members on the companion gastroenemii of the same 

 animal, and each experiment was repeated three times, and often 

 five or six times. The amounts of the nitrites employed varied be- 

 tween 5 V and -^ c.c. 



Several series of concordant results have thus been obtained which 

 lead to two different orders of activity, viz., (1) with reference to 

 the extent to which equal quantities of nitrites shorten the 

 resting muscle, and (2) with reference to the rapidity with 

 which the shortening is produced. The order of activity of the 

 nitrites as regards the extent of the shortening they induce is as 

 follows :(i) Iso-butyl, (ii) tertiary amyl, (iii) secondary butyl, 

 (iv) secondary propyl, (v) propyl, (vi) tertiary butyl, (vii) butyl 

 (viii) a-amyl, (ix) /?-amyl, (x) ethyl, (xi) methyl. The order 

 representing the speed with which shortening occurs is (i) methyl, 

 (ii) ethyl, (iii) secondary propyl, (iv) tertiary amyl, (v) primary 

 propyl, (vi) tertiary butyl, (vii) secondary butyl, (viii) a-amyl, 

 (ix) /3-amyl, (x) primary butyl, (xi) iso-butyl. 



The effect of these nitrites in interfering with the active contrac- 

 tion of a stimulated muscle has also been studied, and it has been 

 ascertained that very minute doses, insufficient to cause passive con- 

 traction, interfere in a marked degree with the active contraction 

 and cause the muscle to fail in responding to stimulation, whilst the 

 companion muscle, contained in a closed chamber free from nitrite 

 vapour, still responded to stimulation. 



The remainder of the paper is devoted to a discussion of the con- 

 nexion between the various phases of physiological action and the 

 chemical constitution of the nitrites which give rise to them. This 

 discussion cannot be adequately abstracted. The principal conclu- 

 sions which have been arrived at are briefly as follows: The 

 physiological action of these nitrites is not solely, and in some cases 

 not even mainly, dependent on the amount of nitroxyl (N0 2 ) they 

 contain. 



In respect of all phases of physiological activity, the secondary and 

 tertiary nitrites are more powerful than the corresponding primary 

 compounds. This is to be chiefly attributed not to the direct physio- 

 logical action of the secondary and tertiary groups, but to the great 

 facility with which these compounds suffer decomposition mainly 

 into the alcohol and nitrous acid. In respect of the acceleration of 

 the pulse, the power of the nitrites is directly as their molecular 

 weight, and inversely as the quantity of nitroxyl they contain. They, 

 therefore, fall into an order of physiological activity which is identical 

 with that in which they stand in the homologous series. This same 

 relationship, increase of physiological activity corresponding with 

 rise in molecular weight, may also be traced, though less uniformly, 



