152 M^IXTOSH^ ON YOUNG SALMON. 



fish. They immediately evinced symptoms of extreme dis- 

 tress, with a tendency to turn on the side. The motion of 

 the pectoral fins was sometimes arrested, and the organs 

 pressed close to the body. The respiratory movements of the 

 lower jaAv became slower and slower ; starting and gasping 

 occurred, and the operculum was stretched outwards to the 

 utmost. Though placed under running water while still 

 able to jerk, they did not recover. 



Chloric ether (one drachm to one ounce of water) caused 

 congestion of the cardiac cavities and great diminution in 

 the frequency of pulsation, viz., from 90 to 30 per 

 minute in a quarter of an hour. In forty minutes the con- 

 tractions almost ceased, and both cavities were gorged. After 

 immersion in running water the heart began to act more 

 rapidly, but recovery was gradual,, the pulsations only 

 amounting to 32 in three quarters of an hour. 



Death ensued very speedily when a little ammonia (liquor) 

 was added to the water, after spasmodic and violent motions. 

 Though plunged in cold water within a minute, recovery did 

 not ensue. The mouth remained widely distended after death, 

 and the branchiae gorged with dark blood. 



Ten minims of foreshat, added to half an ounce of water, 

 produced at first an instant action, with increase of cardiac 

 movements, but the animal soon lay still. The heart's action 

 gradually slowed, the large trunk sending off the blood into 

 the capillary branches ff") with less and less force, so that 

 the latter almost disappeared from sight. Sometimes only a 

 single disc at a time passed along the vessel, whereas many 

 passed formerly. Eetrogade and oscillatory movements 

 appeared in the vessels, and the cardiac congestion increased. 

 Both cavities remained distended after death, which occurred 

 in a quarter of an hour or less. 



When young fish about twelve days old are placed in pure 

 sea water they display little irritability, swimming round the 

 vessel perhaps once or twice, and then quietly resting on the 

 bottom. For the first five or six hours little change is 

 observed beyond a tendency to repose speedily after exertion. 

 Towards the seventh hour there is a considerable diminution 

 in activity, yet the animal readily responds to irritation. The 

 heart's action, which in the fresh water had been 92, 

 has now sunk to 60; both cavities are well filled, and, 

 though rather feeble, the contractions are rhythmical. The 

 pulsations steadily decrease ; and in ten or twelve hours the 

 animal lies motionless. It is likewise apparent that the 

 cutaneous textures are shrivelled and rendered more or less 

 opaque. The mouth gapes, and the pectoral fins stand stiffly 



