150 m'ixtosh, on young salmon. 



alone, and they certainly were much stimulated at the begin- 

 ning. The increase of the auricular and the diminution of 

 the ventricular action were independent of the respiratory 

 process, as I have seen the latter in full action, while the 

 ventricle contracted only half as frequently as the auricle. 

 The action of the poison on the ventricular fibres is peculiar, 

 yet, though produced in a circuitous manner, it is analogous 

 to that on the ordinary muscles. 



Tincture of digitalis, in doses varying from three to seven 

 minims in two drachms of water, first causes symptoms of 

 irritation, the animal darting vehemently round the vessel, 

 and wriggling convulsively. If the dose is small the rapidity 

 of the heart's action is for a time increased during the period 

 of excitement ; and the respiratory movements of the lower 

 jaw are likewise very rapid, indeed in some instances so rapid 

 that they would seem to be inefi'ectual or impede respiration. 

 According to the strength of the dose, in ten or fifteen 

 minutes the cavities of the heart become loaded, the 

 pulsations much diminished in frequency and irregular, 

 the contractions falling, perhaps, from 110 to 60, and 

 even lower.* There is a decided failure in the power of 

 the ventricular contractions, and the cavity seldom empties 

 itself completely. Moreover, shortly after this it could often 

 be observed that both cavities contracted at the same time, 

 unless the dose was minute, e. g. a single minim, in which 

 case the contractions were slightly alternate. Coincident 

 with the retardation of the heart's action is loss of power iu 

 the voluntary muscles and the diminution of respiratory 

 eflfi)rts in the pectoral fins and jaw. After a time the auricular 

 action is more vigorous and sharp than the ventricular, the 

 latter being somewhat distended. The action of the heart 

 gradually grows feebler, and generally ceases in about an 

 hour ; and even with a dose of only one minim death occurs 

 within an hour and a half. 



A probe was dipped in creasote and the small adhprent 

 quantity (less than one minim; mixed with the two drachms 

 of water. "When the fish is immersed therein the first 

 symptoms are those of irritation, the animal darting about 

 and wriggling spasmodically ; violent tremors and jerking 

 also occur. In three or four minutes the heart's action had 

 been reduced from 90 to 50 per minute, but was regular, 

 the ventricle slowlv contracting? after distension. The cardiac 

 action grndually failed, and v. .luntary motion became indis- 

 tinct. After the auricle contracts and is dilating, l)lood flows 

 into it by the auriculo-ventricular opening before the ven- 

 * Compare witli effects on man, ' Poisons,' by Prof. Christison, p. 633. 



