Action of Tobacco Smoke 339 



these effects of nicotine, we know, are due to excitation of the ganglion- 

 cells. The collidine effect bears a superficial resemblance to that of nicotine, 

 except that the inhibition is more pronounced in the case of collidine (B) ; 

 but there is one important difference in the complete absence of rise of 

 tonus. 



The action on the isolated mammal's heart was determined by perfusing 

 the hearts of rabbits with Ringer's solution, by means of a modified Langeu- 

 dorff apparatus. 



At A, in fig. 2, 2 ac. of a 1 per cent, solution of pyridine were injected 

 by means of the lateral tube, but on its reaching the heart only a very 

 small effect was noticed — there was no alteration in tonus, but there was 

 evidence of some quickening of the beats. After a period of 20 minutes' 

 perfusion with Ringer's solution, during which time the heart's action had 

 become quite normal, 2 c.c. of 1 per cent, solution of collidine were injected 

 at B, at the same rate as before,'»into the perfusing fluid. The heart was 

 immediately inhibited in diastole ; but, after the drug had passed through, 

 recovery grad\ially ensued until the normal ihythm w.as regained, no 

 permanent depression resulted. After a further periotl of 20 minutes' rest, 

 2 c.c. of a 1 per cent, solution of nicotine were injected (at C) ; the strength 

 of the heart was immediately increased, the heart-beat was accelerated, and 

 the tonus was gradually raised ; indeed, this gradual increase of tonus with 

 nicotine is a most characteristic effect, and affords a marked distinction 

 between the action of nicotine and the other constituents of tobacco smoke. 



The periods of inhibition found in the tracing, following injection of 

 nicotine, are due to excitation of the intracardiac ganglion-cells ; they are 

 not seen in the atropinised animal. 



I now propose to compare the action of a solution of nicotine with a 

 solution through which tobacco smoke has been drawn. For this purpose 

 the smoke from 1 gram of tobacco, slowly burnt, was drawn slowly through 

 100 c.c. of saline solution. The isolated rabbit's heart was again used ; 

 fig. 3 illustrates the two effects, at A the effect of injecting the smoke 

 solution being shown, and at B the effect of nicotine. The first effect (A) 

 shows initial inhibition followed by accelerati'ni of tiie heart and some 

 increase in strength of the beat : there is no rise in tonus. B shows 

 an almost identical result, but with the difference that the heart does 

 not relax properly in diastole, so that the diastolic tone gradually rises. 

 We know that the pyridine bases, especially collidine, reduce t^.mus in 

 muscle, and it seems possible that while the inhibition and subsequent 

 acceleration shown at A may be due to nicotine, the absence of increased 

 tonus may result from the antagonistic action of the pyridine bases to 

 nicotine. 



iii. Some Effects of Perfusion. — The blood-vessels of the frog were 

 perfused through the right innominate artery, and the outflow from the 

 veins determined by placing the frog in a funnel and allowing the drops to 

 fall upon a lever that recorded on a slowly moving drum. 



VOL. I.. NO. 4. — 1908. 23 



