258 



THE POPULAR EDUCATOK. 



observation of the habits of animals will soon lead us to suspect 

 our error. The sense seems to be the keenest in the camivora, 

 and man is so sensible of his inferiority to these in the sense of 

 smell, that he supplements his deficiency by their acuteness. 

 The little terrier will inform his master, the rat-catcher, if the 

 rat is at home, by his impatient scratching at the mouth of the 

 hole. The huntsman sees a fox cross an alley in a wood; 

 jieynard has gone he knows not whither, and has left no trace 

 which is available to his dull sense. But a hound comes in sight, 

 and when motioned to the place he sniffs the ground in uncer- 

 tainty but for a moment, and then flings up his nose towards 

 the sky, and with one long, melancholy howl calls his comrades 

 of the pack, and, in almost less time than it takes to write it, 

 they are all in full cry on the trail, making the echoes ring with 

 their confident music. Who has not observed the pointer, as 

 he stops in the midst of his swift, business-like beat, motion- 

 less, as if Medusa's head had turned him to stone ? Yet, if 

 you mark him well, his whole frame is instinct with tremulous 

 emotion ; his eyes glisten, and seem starting from his head ; 

 his nostrils twitch, and his limbs quake with' excitement. The 

 game lies hidden in deep cover; it is impossible for him to see it; 

 but as you look at him you feel certain that he is as vividly 

 conscious of its presence, as if his eye saw, or Ms foot were 

 upon it. 



We have seen, in writing of the other senses, that while beasts 

 Beem to have these in greater efficiency than men, this is 

 because their attention is not abstracted from their indications, 

 and not because the organ is any more perfect or elaborate 

 in its structure ; but in the case of the smell, a corresponding 

 development and complication of structure accompanies a keener 

 sense. The great difference between the skull of man and that 

 of the beast consists in the fact, that in the latter the brain and 

 the brain-case which it accurately fits are much smaller ; the 

 jaws and therefore the hollow of the mouth are much larger 

 and longer. Now, the nasal cavity which lies between these 

 partakes, in the beast, of the elongation of the jaws, and not of 

 the curtailment of the brain. The nose is almost always at the 

 end of the muzzle, and the long chambers of the nose only pass 

 under the brain -at the posterior part of their course, where they 

 also begin to descend to enter the throat. Hence, instead of 

 comparing the face to a three-storeyed house, as we did in 

 speaking of the man, it should be compared to a two-storeyed 

 shed, with a lean-to behind for the accommodation of the brain. 

 The turbinated bones are, therefore, not so much one above as one 

 behind the other, the front or inferior one being very much enlarged 

 and contorted, or folded, so as to fill up the large chamber. This 

 bone is very differently shaped in the different animals. In the 

 sheep it arises by a broad plate, which runs inward from the 

 outer wall of the nose, and then divides into two plates, both of 

 which assume the form of scrolls, one curling upwards and the 

 other downwards ; and the number of turns of these scrolls is so 

 great, that if a transverse section of the nose be made, the edge 

 of the bone looks like the capital of an Ionic column. In the 

 hare and rabbit the bone has a different form, and consists of a 

 number of plates one above the other, which subdivide into 

 other smaller horizontal plates or ridges, all of which are, so to 

 speak, gathered together into one stem at each end. The seal 

 has a bone of the same structure, but much more subdivided 

 and complicated ; and the extraordinary development of the 

 organ in these swimming carnivora, would lead us to suppose 

 that they hunt by scent. It will be seen that the design of all 

 these structures, however different their form may be, is to 

 increase the surface over which the pituitary membrane, as it is 

 called, can be spread. Now, in man, the membrane of the lower 

 scroll-bone is not so specially the seat of the organ of smell as 

 of a refined and acute sense of touch; for the nerve which 

 supplies it is not from the olfactory bulb, but from the fifth pair 

 of nerves. It is this nerve which is excited by the application 

 of snuff : so that the snuff does not act as an odour, but as an 

 irritant, and the pleasure may be compared, by those who do not 

 appreciate it, to the pleasure of scratching in other parts of 

 the body. In beasts, however, the nasal branch from the iifth 

 pair of nerves would seem to be a nerve of special sense ; and, 

 besides this, since the turbinated bones are not one above, but 

 one behind the other, the air passes successively over them all, 

 instead of below the ethmo, or upper turbinated bones, as in man. 

 Perhaps it is not out of place here to remark upon some 

 functions discharged by the nose, which are not olfactory. In 



the porpoise the brain has no olfactory lobe, and there are no 

 olfactory nerves; and therefore the nasal passages are made 

 subservient to the supply of the lungs with air. A reference to 

 the engraving will show how the canal from the slit-like opening 

 at the top of the head passes down past a valve, which closes it 

 against the water when the animal is submerged, and then 

 onward to the head of the windpipe, which here does not open 

 on the floor of the oesophagus (or food- throat), but is continued 

 up, and thrust into, the nasal canal, while the muscles of the 

 soft palate and food-throat grasp it firmly. If the animal 

 chooses, however ; he can force the water from his mouth past 

 this perforated plug, and make it issue in a stream from the 

 blow-hole. Though the function of smelling seems to be thus 

 entirely sacrificed to other uses, in the nose of the whale and 

 porpoise, it will be seen from the engraving that an orifice lead- 

 ing from the part of the canal external to the valve passes 

 into a chamber, upon whose folded sides a membrane is spread 

 which has branches of the fifth pair of nerves distributed to it. 

 Through this organ, no doubt, the porpoise can test the purity 

 of the water in which it is immersed. 



The hog uses his disc-shaped snout to turn up the earth, and 

 the tapir curls his flexible nose round the grass to tear it up; 

 but these slight differences from the usual development of the 

 organ sink into insignificance beside the enormously elongated 

 trunk of the elephant. In this beast, the two narrow tubes 

 into which the nasal chambers are continued forward, run to the 

 very end of the organ, where there is, on the upper side, a finger, 

 which seems to be as serviceable as any of our own. Strong 

 bundles of muscles run along the trunk on all sides, and 

 radiating ones pass between these, so that the beast can move 

 his trunk in any direction he pleases. 



In birds the sense of smell is by no means so efficient as in 

 mammals. This we may pronounce with certainty, because not 

 only is the organ, and its accessory apparatus, less developed, 

 but the habits of birds indicate that they are but little guided 

 by the sense of smell. Eaptorial birds, like flesh-eating animals, 

 have better-developed olfactory organs than grain-feeding fowls. 

 The main nerve of smell of the vulture is five times the thick- 

 ness of that of the turkey, although the carrion-feeding bird 

 (first-named) does not exceed the other in weight ; but it would 

 seem that this sense in the vulture and condor is only useful to 

 them in selecting while at their meal, and does not guide them 

 to the meal itself. A number of confined condors had some 

 steaks of flesh, wrapped in paper, placed before them, but they 

 gave no sign of being aware of their presence ; when, however, 

 the paper was removed, they were seen tumbling over one 

 another in their eagerness to snatch the food. 



The general peculiarities of the organ of smell of birds are 

 the following : The nerve leaves the skull by one hole, and not 

 through many, as in beasts ; the membrane to which the nerve 

 of smell goes is confined to the base of the beak, and the outer 

 nostrils are not at the end, but at its sides or base ; and though 

 these nostrils are sometimes protected by a scale (as in the 

 pheasant), or a sheath (as in the stormy petrel), or a bunch of 

 stiff feathers (as in the raven), there are never any flexible 

 cartilages moved by muscles. That singular wingless bird, 

 thence called the apteryx, affords the only exception to the 

 above statements, for its nostrils are at the end of its bill, the 

 upper turbinated bones are of very large size, and many nerves 

 pierce the skull, as in the mammalia. These peculiarities indi- 

 cate greater acuteness in the sense of smell; and this is 

 thought to. be associated with its habit of probing among loose 

 earth, to hunt for worms, by scenting them. 



In the pelican there are no external nostrils whatever ; and 

 this is, no doubt, reasonably accounted for by the fact that this 

 bird fishes under water with its long bill, and detains its prey 

 for inspection in its capacious pouch. While in this position, 

 the contents of the bill send off effluvia to the nose by the back 

 way of the palate ; and since the nostrils of the bird, if it had 

 any, would be above the water, and its prey below it, they could 

 be of no service. 



In the higher reptiles, the internal organ is very like that of 

 birds ; but in some the nostrils are wide apart, and in others, as 

 in all the crocodiles, they are united into one, which in the true 

 crocodile of the Nile is shaped like a half-moon, and closed 

 by a valve from behind ; and in the gavial, or slender-snouted 

 crocodile of the Ganges, the skin round the nostril can be raised 

 so as to allow it to be just lifted above the surface, while the 



