Ad. S. Jensen: The Selachians of Greenland. 13 



they may be very bad from it. From dried shark flesh the dogs never become •'shark- 

 intoxicated", yet they can also become sick from it, as dried shark meat tends to swell 

 out in the stomaciis of the dogs; the Greeiilanders therefore advise to give the 

 dogs only small rations of dried shark meat and first to cut the meat into long and 

 narrow strips, so that the dogs do not gulp down the whole at once, but can regularly 

 work through it with the teeth^). 



To explain these phenomena it may be said, that the fresh shark flesh contains a 

 compound that acts like alcohol; when the flesh is boiled, the poisonous stuff is removed 

 and the dogs can then eat more of it without suffering than when the meat is fresh. 

 The poisonous substance is probably present everywhere in the body of the shark, 

 also in the cartilage. Rink was of the opinion, that the danger of the shark's flesh 

 was due to its containing a large amount of saline fluids, which were totally swallowed 

 down when the flesh was eaten in the frozen condition^). To clear up the matter I 

 consulted the veterinary surgeon S. Hjorti.und, who lived for a couple of years in 

 North Greenland and there made investigations on the infectious sicknesses of the 

 dogs; he has kindly sent me the following information. 



"These cases of poisoning, which in Greenland always occur after eating fresh, raw 

 meat of the Greenland shark (Sontniosiis microcephalus), both in men and dogs, is without 

 doubt due to a specific poison (a toxin 1 which occurs in its body. Nothing indicates 

 the correctness of Rink's view, that the poisonous nature of fresh shark meat was due 

 to the large quantity of saline fluids it contained, whilst many things sjieak against this 

 view. 



Meanwhile, iiowever, the question has not yet been scientifically investigated and 

 all we know about it is exclusively based on empirical observations. 



The clinical symptoms, of which — as mentioned above — tiredness, dullness, un- 

 certain gait, sensory disturbances and a profuse diarrhoea are the most in evidence, 

 depend in virulence on the quantity of meat taken, but in dogs can also be intensified 

 in mild weather and with bodily exertion. In men. where the poison causes a similar 

 complex of symptoms, the sense disturliaiices both objectively and subjectively give 

 the same impression as acute alcohol poisoning. The symptoms of |)oisoning may last 

 a shorter or longer time, from a couple of hours to a couple of days. They may be very 

 weak, almost unnoticeable, when the animal has only taken a small quantity; on the 

 other hand dogs have several times been known to die under violent symptoms, almost 

 apoplectic in character, a short time after they had eaten large qiianlities of shark meat, 



') A part of thi.s information I owe to kind communications from the Director of the 

 colonies of Greenland .1. Daugaard-Jensen and the Colonial Governor P. Ibsen, who have lived 

 many years in North Greenland and thus had excellent ojiportunities lo become well-acqnainted 

 witli the sledge-dogs. 



-) Rink 1. c. p. i;-5i). 



