144 Canadian Record of Science. 



is a cardiac excitant, potassium carbonate a depressant. 

 The former tends to quicken the beats and diminish diastole. 

 A heart arrested in diastole by potassium carbonate may be 

 excited to action by sodium carbonate. Potassium carbonate 

 must be regarded as a cardiac poison. 



Lactic Acid. (1) In five per cent, solution this is a rapid 

 cardiac poison. (2) In one per cent, solution its action is 

 slower, but it proves a decided depressant, and the heart 

 arrested by lactic acid cannot be excited to action by 

 digitalis, sodium carbonate, &c. 



Nicotin in one per cent, solution. (1) Its first action was 

 often to arrest the heart in diastole. (2) This was some- 

 times followed by an irregular, slowed rhythm giving way 

 to a more rapid but weaker heart beat. But the fish heart 

 shows great power of resistance against the effect of nicotin 

 in weak solution and can, it would seem, recover almost 

 wholly from the effect of this poison. Nicotin tends strongly 

 to produce inco-ordination of the beat. 



Chloroform (undiluted) acts as a decided cardiac depres- 

 sant, tending to arrest the heart in diastole. The heart can, 

 however, recover fairly well from a considerable quantity of 

 this poison applied directly to it. 



Acetate of Strychnia in one percent, solution. This poison 

 did not seem to have the most pronounced action, but tended 

 to strengthen the systole, diminish diastole and arrest the 

 heart in systole. 



Yer atria in rather less than one per cent, solution. The 

 most distinct action is on the diastole, which it retards. 

 The heart in action has a generally sluggish movement 

 rather than a weakened one ; the systole may in fact be 

 slightly improved. It also tends to cause arythmic pheno- 

 mena — want of harmony in the sequence of the beats of 

 different parts and of different fibres in the same part, e. g., 

 there may be two or more beats of the auricle for one 

 of the ventricle, &c, or one part of the ventricle may be 

 pulsating out of harmony with the rest. 



Digitalin in somewhat less than one per cent, solution has 

 more than any other of the agents tested a constant, decided 

 and well-defined action. (1) A short time elapses before its 



