m'iNTOSHj ON YOUNG SALMON. 15 



Q 



out at right angles to the body. Both cavities of the heart 

 are gorged with blood, and though in some there are 

 feeble contractions (from 15 to 20 per minute), the dark 

 central mass is never dispelled from either chamber. This 

 congestion is doubtless augmented by the shrivelling of the 

 superficial textures of the body. In other cases the action 

 of the heart becomes intermittent before ceasing, remaining 

 inactive for a time, with the auricle dark and distended to 

 the utmost, the ventricle also dark, but less bulky, but by- 

 and-by it begins to contract, and pvdsates, perhaps, for forty 

 times, and again suddenly ceases, while the feeble circulation 

 — for the moment set agoing — is arrested. No other action 

 of a vital natvire could be elicited. The most remarkable 

 change, however, is that which ensues in the yolk-sac before 

 death. This consists of an alteration in its form (from a short 

 to a more elongated condition) , and Avhat may be termed a 

 coagulation of its contents, w^hich become at first doughy, so 

 that after being dimpled by a glass rod the outline is re- 

 covered very slowly, and finally resiling from the touch of the 

 rod like a rounded and smooth bit of cartilage. Some, indeed, 

 resemble a mass of amber, having a clear yellow aspect, and, 

 when punctured, are not much softer than a fresh lens. 

 Death in this case would seem to arise from cardiac conges- 

 tion, aggravated by the shrivelling of the cutaneous textures 

 and consequent shutting up of the blood-channels ; and, 

 secondly, from interference with nutrition, arising from the 

 change in the condition of the yolk-sac* 



Several young salmon were allowed to touch the tentacles 

 of an Actinia (Tealia crassicornis), and then removed ; in all 

 the instances death seemed to result sloAvly from the physical 

 injuries inflicted by the dart-cells on the brain and other 

 organs. The influence of a subtle poison or paralysing 

 agent, at any rate, was not apparent. 



Operations. — When the tail of a young salmon, from eight 

 to twelve days old, was cut off" at any point behind the bend 

 of the corda (e. g. through the dotted line A b), the following 

 effects ensued : — The animal did not wriggle much, and soon 

 rested; an immediate eff'usion of blood occurred from the 

 ends of the divided vessels, and by-and-by, in some, four or 

 five rounded knobs of blood, or clots, projected from the ends 

 of the vessels, or else a general mass of clot along the cut 



* In a sketcli of tlie natural history of tlie Salmo salar, by Daniel Ellis, 

 drawn up from evidence contained in two re|)orts of a Select Connnittee of 

 the House of Commons, &c. (Jameson's ' Edin. Philos. Jour., vol. iv), it is 

 mentioned that when ova were put in salt water none came to life, and that 

 when a young hatched fish was similarly dealt with it died in a few hours. 



