146 m'intosh, on young salmon. 



were added to a vessel containing two drachms of water, and 

 the chief features of its action were similar in all cases. 

 The young fish experimented with were from two to six 

 days old. 



In the healthy animal, before adding the poison to the 

 water, the action of the heart is quite regular, the con- 

 traction of the ventricle {a, PI. Ill) succeeding that of the 

 auricle {b) in a methodical manner, and varying from 70 

 to 100 per minute; the pectoral fins are also kept in rapid, 

 whirring motion. In a few seconds after the addition of the 

 aconite the young fish showed symptoms of uneasiness, dart- 

 ing round the vessel, jerking its head, and twitching its body 

 and tail. The violent exertions of the animal increased the 

 frequency of the heart's action, and caused congestion of 

 both cavities; but for a time the action of the organ Avas 

 rhythmical. Before the expiry of ten minutes, however, it 

 could generally be observed that there was a tendency to 

 irregular action of the heart, both cavities occasionally con- 

 tracting at once. The respiratory movements, as evinced by 

 the action of the lower jaw, became very hurried, but the 

 flapjjing of the pectoral fins was sloAver. In about a quarter 

 of an hour the animal does not respond to irritation, unless 

 the dose has been very small, pressure on the yolk-sac only 

 causing a slight twitch. A diminution in the frequency of 

 the heart's action was noted in some at this time. A very 

 remarkable symptom now appeared, viz. a tendency to a 

 more rapid motion in the auricle, with a retardation ofthe 

 ventricular movement, and this became more marked as the 

 paralysis of the muscles of voluntary motion increased. 



When a sii)gle minim of the tincture Avas added the in- 

 crease of auricular and diminution of ventricular action ap- 

 peared move slowly, generally within an hour, at which 

 period, e. g., the beats of the auricle in one instance were 1^4, 

 those of the ventricle (i2. The auricle resembles a circular 

 caoutchouc bag in a state of rapid contraction and dilatation, 

 while the ventricle retains its shape, but is less vigorous than 

 in the normal animal, especially, in some instances, as re- 

 gards every alternate contraction. Complete paralysis did 

 not ensue with such small doses for a long time, though the 

 fish kept its body motionless, the pectoral fins being in rajnd 

 vibration, and the respiratory movements of the lower jaw 

 very hurried. This state continued fir many hours, the jaw 

 moving 160 times in a minute, and the pectoral fins resem- 

 bling the rapidly vibrating wings of a butterfly or humming 

 bird. This vibratory action now and then became intermit- 

 tent ; but the animal gradually loses the power of responding 



