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THE POPULAR EDUCATOR. 



the adult state there is a succession of colour and pattern 

 changes of its coat. When born it has a white woolly covering, 

 which in the first year changes to a cream colour ; in the 

 second year it has become grey; in the third painted with 

 stripes ; in the fourth, spotted ; and in the fifth year it has the 

 peculiar half-moon markings which show thatit has reached matu- 

 rity. These markings are so distinct in separate years that it 

 will be quite understood that one may readily tell the age of a 

 Greenland seal by means of them. It is this species which is 

 of such great importance to the Eskimo, so that he hunts it on 

 all available occasions, launching out to sea in his frail skin- 

 covered boat for that purpose, and harpooning the seals as 

 they come to the surface to breathe ; or enveloping himself in 

 a seal's skin and lying on the shore, in order to attract some 

 unwary seal, which is thus lured to destruction ; or by making 

 a hole in the sheet ice, and patiently waiting and watching 

 until a seal presents itself to breathe, when it is at once seized. 

 When captured it is put to the various uses we have already 

 described. 



The Capucin Seal is so named because it has on its head, in 

 bhe full-grown state, a peculiar organ in the shape of a hood, 

 with which it can cover its muzzle when it chooses. Its pecu- 

 liarities, however, do not end here. It can distend its nostrils 

 in such a way as to give them the appearance of a bladder. It 

 has also a structural peculiarity of the eyes, which is not a 

 little puzzling. In order that we may perfectly understand it, 

 we shall here make a short digression on visual organs and 

 vision in general. In the inside of every vertebrate eye there 

 is formed a picture of such external objects as the vertebrate 

 may be looking at. The organic mechanism by means of which 

 this is managed is beautiful and simple. Inside the eye there 

 is a lens, held in position by transparent humours on either 

 side of it, and more particularly by an elastic frame, which 

 holds the lens just as a spectacle-frame holds its double convex 

 glass lens. And the crystalline lens within the eye throws a 

 picture of external objects on to the back of the eye, just as 

 the spectacle-glass may be made to throw an image on to a 

 white sheet of paper. The latter experiment is interesting, and 

 the reader may therefore try it in this manner : Go into a dark 

 room with a sheet of note-paper, a candle, and a pair of spec- 

 tacles with double-convex lenses, i.e., glasses thicker in the 

 middle than at the rim. Having put down the candle, hold 

 the sheet of paper a few feet away, and in between adjust 

 one of the spectacle-glasses until an image of the candle 

 upside down is seen on the paper. What is happening here in 

 this experiment is happening within your eye when you look at 

 the candle. The lens within the eye is throwing an inverted 

 image of the candle on to the back of the eye, and the impres- 

 sion produced is carried away in a mysterious manner by a 

 large nerve, called the optic-nerve, to the brain. The expansion 

 at the back of the eye upon which the picture is cast is called 

 the retina. The retina is most sensitive exactly in the centre, 

 and a little on one side of this centre the optic-nerve enters. 

 Now the spot where the optic-nerve enters is blind, so that 

 one would naturally suppose it would have been a most unlucky 

 thing for the animal kingdom had the optic-nerve entered the 

 back of the eye exactly at its centre, for what is the most used 

 portion of the eye would thus have been made blind.. It is a 

 strange thing, however, that this is exactly what is found to be 

 the case with the Capucin seal. The optic-nerve enters at the 

 back, exactly in the centre of the eye. Since, however, this 

 seal is not blind, there must be some compensatory arrangement, 

 and it appears to us not improbable that this may be found 

 either in some external or internal divergence from the usual 

 kind of eye. The external covering of the Capncin's eye, which 

 is usually known as the sclerotic coat, is divided at its middle 

 all round, the edges of the two hemispheres thus produced 

 being connected by an elastic membrane thickly covered by 

 muscles. It is supposed that these muscles are employed for 

 drawing the eye deep within the socket during repose, and also 

 for elongating the axis of vision, i.e., lengthening the line passing 

 through the centres of the lens and retina. May it not also 

 have some hand in compensating for the peculiarity we have 

 just mentioned, viz., the entrance of the optic-nerve into the 

 central region of the retina ? This, however, is an undecided 

 matter, which we may well leave in the hands of those of our 

 readers who hereafter shall become well versed in physiological 

 optics. Capucin seals occur in large numbers in Davis' Straits, 



at certain times of the year. They are commonly found on 

 large ice-islands, where they sleep without taking any precau- 

 tions against the Eskimo seal-hunters. When surprised, they 

 weep copiously. A full-grown Capucin seal is from seven to 

 eight feet long. 



The Elephant Seal of South Seas is the largest known species, 

 being from twenty to thirty feet long, and the largest part of 

 the body having a girth of twenty to thirty feet. The nose of 

 the male is prolonged into a kind of trunk, but the female has 

 no proboscis. It is much hunted for the oil it will yield, a full- 

 grown male furnishing as much as seventy gallons. The skin 

 is of little value as a fur, but is extensively used for carriage 

 and horse harness, on account of its strength and thickness. 



The Sea-bear,, which is from four to seven and a half feet 

 long, is common in the islands on the north-west point of 

 America, Kamtschatka, and the Kurile Islands. Its soft brown 

 fur is highly valued in China, and on this account the Russians 

 hunt it with a zeal which may ultimately lead to its extinction. 

 In common with a host of other animals, its fur becomes tinged 

 with grey on the approach of old age, the tips of the hairs being 

 most changed. It has external ears nearly a couple of inches 

 long; they are conical, erect, covered with short hair, and 

 opened by an oblong slit, which is shut in the water. The sea- 

 bears are migratory in their habits, and when they arrive in 

 spring on the shores of the islands we have mentioned, they are 

 in high condition. They live in families, each male being sur- 

 rounded by some fifty to eighty females. Each family, number- 

 ing over a hundred members, lives separately, and jealously 

 guards the particular locality it may have taken up on the 

 shore against the encroachments of any other family. Family 

 squabbles are common, as the male appears to be somewhat of 

 a tyrant, but both male and females are affectionate to the 

 young. The flippers of the sea-bear become of sufficient size 

 and power to enable the animal to progress in the water by 

 their aid alone. It appears to fly in the water, for these 

 flippers, when elevated and depressed in the water, twist and 

 untwist precisely as wings do. The feet and lower portions of 

 the body are moved only sufficiently to maintain a correct course, 

 or alter it if necessary. 



No matter what branch of science a man may study, it is 

 always a matter of the keenest interest to him to turn back and 

 compare what is known at the present with what was known in 

 times long past, as set forth in some ancient book of established 

 repute. Let us, then, in the present instance not deny our- 

 selves this pleasure, but turn to Pliny and see what that 

 naturalist had to say about seals more than eighteen centuries 

 ago. In the 15th chapter of the 9th book of his " Natural 

 History," after speaking of the birth and education of the 

 young seal, he goes on to observe that "these animals are 

 killed with the greatest difficulty, unless the head is cut off at 

 once. They make a noise which sounds like lowing, whence 

 their name of ' sea-calf.' They are susceptible, however, of 

 training, and with their voice, as well as by gestures, can be 

 taught to salute the public ; when called by their name they 

 answer with a discordant kind of grunt. No animal has a 

 deeper sleep than this ; on dry land it creeps along as though 

 on feet, by the aid of what it uses as fins when in the sea. Its 

 skin, even when separated from the body, is said to retain a 

 certain sensitive sympathy with the sea, and at the reflux of 

 the tide, the hair on it always rises upright ; in addition to 

 which, it is said that there is in the right fin a certain sopori- 

 ferous influence, and that, if placed under the head, it induces 

 sleep." The nineteenth-century reader will smile at the very 

 idea of reposing on a seal's flipper in order to induce sweet 

 sleep ! 



Now come we to speak of the Walrus, or Morse, an animal 

 which resembles the seal in the general structure of its 

 skeleton. There is a striking difference, however, in the 

 cranium and teeth, the latter being very manifest in the couple 

 of tusks projecting from the upper jaw, which form a very 

 powerful instrument of attack and defence. These tusks are 

 canine teeth developed to an extraordinary extent. They are 

 sometimes two feet long, stout, and solid, with large roots, of 

 which the sockets project considerably, giving a swollen aspect to 

 the face. It is these large sockets which give rise to the charac- 

 teristic form of the skull of the walrus. It has no cutting and 

 canine teeth on the under jaw, but eight molar teeth in both 

 upper and lower jaws, which are suited for pounding up hard sub- 



