78 THE FUR SEALS OP THE PKIBILOF ISLANDS. 



It must be remembered, too, that the proportion of 15 to 91 is abnormally high from 

 the fact that in securing specimens for dissection hundreds of obviously starved pups 

 were passed by and others secured when possible. 



Up to the middle of August the number of deaths from Uncinaria exceeds that 

 from all other known natural causes combined, and while many young seals probably 

 recover from attacks of the parasite, it would seem that in a large proportion of cases 

 the disease is sufflciently severe to cause death. 



In the absence of the necessary data, we can say nothing as to the proportion of 

 infected young which recover, and the data could only be obtained by the somewhat 

 expensive method of killing and examining at least one hundred healthy individuals 

 from some such locality as Tolstoi sand flat. Such an examination should begin after 

 August 15 and be continued up to or into September, and the results of the dissections, 

 compared with the number of pups found dead from Uncinaria, would afford some clue 

 as to the proportion which are attacked and recover. The best we can do at present 

 is to glean what we can from the tables of mortality, and here we find that of the 24 

 which died from violence, sundry or unknown causes, 4 contained Uncinaria, although 

 1 contained but a single example. Out of 177 starved pups, 14 contained Uncinaria 

 in numbers too small to be fatal, although these starved pups throw little light on the 

 problem, since, as pointed out elsewhere, the starving animals are the least liable to be 

 infected. We can merely say that of 201 pups which died from various causes, but 

 mainly from starvation, 18 contained small numbers of the parasite. These figures do 

 not include the deaths on St. George, which is almost free from Uncinaria, and for 

 that reason was not considered. 



While many apparently strong and healthy pups suffer from Uncinaria, those 

 dangerously attacked may usually be recognized by their sleepy appearance, the eyes 

 being dull and partly closed ; by the unkempt appearance of the coat, and by their lack 

 of vigor. When it is possible to obtain and handle these animals they are found to lack 

 the spirit and bad temper of healthy animals, to allow themselves to be handled and 

 to apparently enjoy being rubbed. One of the effects of the disease seems to be to 

 make the pups restless and to cause them to wander away from the rookery limits, 

 sometimes to very considerable distances, and it is probable that young seals observed 

 in 1896 and recorded as stragglers were afflicted with a fatal attack of Uncinaria. 



The blood of animals suffering from Uncinaria is small in quantity, deficient in 

 red corpuscles, thin and watery, and in extreme cases will not coagulate. The flesh 

 is ansemic, so much so in typical examples that the cause of death is revealed at the 

 first stroke of the knife; the lungs are pale, the kidneys particularly so. At the same 

 time, while the animals are somewhat flabby, they have every appearance of being 

 well nourished, and unless death has resulted from a combination of Uncinaria and 

 starvation the bodies are enveloped in a thick coat of blubber, death coming so quickly 

 that there is not time to get thin. Thus the pups which have died from Uncinaria 



could exert its influence, but we do not know at what period, if at any period of infancy, the 

 parasite ceases to he fatal to the pup. The presumption is certainly strong that to thjs epidemic 

 cause is due a very considerable proportion of that moiety of deaths which do not constitute but 

 only include the loss from pelagic sealing." The presumption, or, rather, the evidence, is opposed to 

 this "presumption," and even were it true it does not alter the fact that every pup seal whose 

 mother is killed inevitably starves. The argument is that because there is a high natural death 

 rate therefore it does no harm to add to it. ^ 



