before, that the horn had been filled with stones, the oil was gone, and the clay was covered with impressions evidently from the feet of rats.”— American Paper. with a certain mare in Wermeland, which was known to have come off victorious in numerous conflicts. But this animal exhibited extraordinary courage as well as wonderful sagacity; for instinct telling her that her own soft heels would "During the hay harvest in July last, the men have but little effect on Bruin's iron carcase, she who were mowing in one of my fields captured a would not, after passing the winter in the stable, mouse of a very peculiar kind. Its sides were of betake herself to the woods in the spring, until a light-blueish gray, whilst a white streak exduly provided with shoes. But when the black-tended down the whole length of the back, and smith had performed his part, feeling she was also over the head; the neck was surrounded by then prepared to meet the enemy on equal terms, a broad white streak, giving it the appearance of she would trot off gaily to the depths of the a collar. The mouse was thought so great a forest. I have also read of a mare at Wuollerim, curiosity that it was preserved alive, and placed in Jockmock's Lappmark, that was celebrated for in a box such as stuffed birds are kept in, with a thus combatting wild beasts. For the mere fun glass side, and a compartment at one end to serve of the thing, indeed, she would at times become as a sleeping-room, and furnished with a trapthe assailant. On one occasion she slaughtered door, in order to secure the mouse whilst its three wolves which were prowling in company on dining-room was being cleaned out. The little a newly-frozen lake. Though I have never seen fellow soon became perfectly reconciled to his the horse in conflict with the bear or wolf, I can new abode, and apparently very much pleased by well understand that he at times proves a formid-being noticed. A few weeks ago his box was able antagonist; for, independently of his heels, which with management may perhaps be avoided, his fore-legs are most destructive weapons. About two years ago, a horse thus attacked a valuable pointer of mine-a manœuvre possibly learnt in his combats with wolves-in the most savage manner. No dancing master could have brought his legs into play with more agility; and it was only by a miracle that the poor dog escaped de-out of his bed-room, in order that a similar misstruction.-Scandinavian Adventures. SAGACITY OF RATS AND MICE (p. 27).-A volume might be filled with well authenticated instances of the sagacity of these animals, especially of the former of them. The two which follow are fresh to us, and in the latter will be found an answer to the query of our correspondent: "We have heard of numerous and striking instances of the sagacity of rats, but we don't remember any more extraordinary than the following, which has been communicated to us by a gentleman connected with the Peak Forest Canal Company: The workmen of the Crist Quarry, at Buggsworth, which belongs to the Canal Company, have a horn in which they keep oil for the axles of their waggons, &c., which they have been in the habit of placing on the ground in an upright position. To their great surprise, they have several times recently found the horn filled to the brim with very small stones, and nearly the whole of the oil gone. This circumstance puzzled them exceedingly; and in order to discover the way in which the oil had been extracted, they placed the horn, containing a quantity of oil, in its old position, and covered the ground with soft clay. The next morning they found, as cleaned out, the mouse, as usual, being shut up in his bed-room. It so happened that the trapdoor was forgotten, and the poor mouse remained in confinement a day and a night. When his case was discovered, and the communication with his dining-room once more opened, his delight was unbounded: he soon, however, set to work and dragged his bed-composed of some loose tow chance might not again befall him-a degree of forethought which would well become the ma. nagers of some of our railroads."-Correspondent of Church and State Gazette. QUERIES. Wire-Worm.-"A Gardener," who "does not see why we should not make our 'Notes and Queries' as practically useful as they are entercheap recipe for the destruction of the abovetaining and instructive," asks for a good and named pest of cultivators. Will any of our readers favour us with the result of their experience in this matter? between the creatures so designated, or are these Viper and Adder.-Is there really any difference but two names for one and the same reptile? I read that there is but one venomous snake in England, and yet I am told that both the viper and adder are venomous. How is this ?-INQUIRER. The Puff Adder.-This is, I believe, a reptile of South Africa, about the intensity of whose venom wonderful stories are told. Will you furnish me with some account of it?-A READER. The Water Spider.-I have been lately much amused by watching in our aquarium the movements of a Water Spider; and as I like to know as much as possible about the habits of the living much obliged if you will give me some account of creatures which come under my notice, shall feel this.-JOHNNY. THE PHYSIOLOGY OF HEALTH AND DISEASE. CHAPTER THE SECOND. ON THE STRUCTURE OF THE TEETH, ONE of the most striking facts in the structure of all animals, is the relation of one part of their organization to every other. It was the discovery of this fact that gave so much importance to the geological researches of Cuvier. He showed that it was not necessary, in order to know the structure and habits of an animal, that you should either see the living animal, or have even the whole of its remains. He pointed out that a certain structure of the foot required a particular condition of the leg, the pelvis, the spine, and thus on throughout the whole body. The practical value of these researches has been of the most decided kind in deciphering the history of the ancient world. Amongst the remains of animals which have been handed down to us in the greatest number and the highest state of preservation, are their teeth. This has arisen from their dense structure more readily resisting the action of decomposing agencies than any other part of the body. This may be regarded as a fortunate incident for geology, as of all parts of the body the teeth are most decidedly distinctive of the character of the animal. The reason of this arises from the adaptation of the teeth to the peculiar food on which an animal lives. The nature of the food, to a great extent, influences the whole habits of the animal. How different must be the organization of creatures obliged to pursue living animals as their prey, from those which browse on the grass, or feed on the fruits of trees! But the teeth, being adapted to the food, at once suggest the whole structure of the animal. Thus single teeth of animals have been found, and the whole structure of the animals and their habits have been suggested by their examination. It is to the teeth, then, that we wish now to draw attention, as organs connected with the preparation of food in man. The comparative anatomist distinguishes two kinds of teeth; for, on examination of some of the lower animals, he finds that they possess organs which perform some of the same functions, and having a similar structure to those in higher animals, yet having a very dissimilar origin. The teeth of man and the higher animals originate in the bone, in a part of their skeleton; but if we examine the teeth of fishes, we shall find that they do not arise from the skeleton, but from the membrane of the mouth. They are precisely of the same character as the spines seen on the scales of the back of some sharks and rays. These teeth, then, originate in a structure similar to the skin, and are called dermal or skin teeth. They are, however, occasionally very powerful organs, but they are used almost entirely as organs of prehension; they are not attached to a moveable bone, as is the case in the true teeth, and hence they cannot be used for the purpose of mastication. If we examine the teeth of the human jaw (Fig. 6), we shall find that they are a C Fig. 6. representatives of the principal classes of teeth that we find developed in the lower animals. They are of three kinds :-First, the large teeth behind, with broad, flat surfaces, and which, on account of their functions, are called grinders (a); they are technically named molars, or molar teeth. They are altogether twelve in number in the adult jaws, being three on each side of both upper and lower jaw. The last of these teeth are called wisdom-teeth in man, from the fact that they do not appear till from the eighteenth to the thirtieth year of his age. These are followed, on each side of both jaws, with two teeth whose surfaces are less broad, and which, having two sharp projections on each, are called bicuspids-two-pointed (b). The sixth tooth on each side is called the eye-tooth (c) : it has but one point, or projection, hence these teeth are called cuspidate (pointed). From its presence and large development in dogs, it has been called the canine tooth. Between these teeth, on each side, we have four teeth which have neither the broad surfaces of the grinders, nor the points of the cuspidati; but they are flat, having a sharp edge like a knife, hence they have been called incisors (d), or cutting teeth. Now these three sets of teeth, which we may call grinders, tearers, and cutters, represent three classes of teeth amongst the lower animals. The grinders, which are evidently adapted to perform the operation which gives them their name, are found developed to the fullest extent in animals which live wholly upon an herbaceous diet. Thus, all the creatures belonging to the family of the Ruminantia, which includes such wellknown animals as the sheep and the ox, the antelope and the deer, are not only supplied with these teeth, but have them much more fully developed than the other teeth, which are, comparatively, of small size, and in some cases absent. The pachydermatous animals, to which the elephant, rhinoceros, and hippopotamus belong, possess also these teeth of a very large size. In all cases they are employed to break down the coarser kinds of vegetable food before it is finally passed into the stomach for digestion. The pointed teeth, or tearers, are found most perfect in those families of animals which prey on other animals, and live on flesh. The most perfect exemplification of the nature of these teeth is found in the Carnivora, the order to which the lion and tiger belong. In these creatures the eyetooth and bicuspids are very large, and their sharp points fully developed, and adapted to each other on opposite sides of the jaws, so as to serve at once as a powerful means of holding as well as tearing up their living prey. The grinders in these animals are also more or less pointed on their surface. The front teeth - the incisors - are adapted for gnawing and cutting, and we find these teeth especially prominent in the family of rodents, or Rodentia. This family includes the hare and the rabbit, the rat and the squirrel. They live chiefly on vegetable food, and this of a hard nature. Some of them even eat wood; whilst such as the squirrels procure their food by piercing the hard coverings of the seeds of plants, as the various forms of nuts. Other families of animals have a mixture of these various kinds of teeth, according to their food. Although the teeth form so prominent and distinguishing a feature of all the fullgrown individuals of the higher forms of animals, yet most of these animals, including man, are born without any teeth at all. When the child is born, the jaw is covered with gums, but underneath the gums are little cavities in which the teeth are formed; and as they go on growing, they at last press upon the gum, and causing it to absorb finally break through it. This process is called dentition. It is frequently a source of disordered health to children, especially if anything occurs to prevent the absorption and ready yielding of the gum to the pressure of the tooth below. The absence of teeth during the period of human infancy evidently indicates that the food required at that period does not need their employment. It is a well-known fact, that the food of the infant is its mother's milk; but it is too often forgotten that, till teeth are developed, Nature does not intend the child to take food that requires preparation by teeth in order to its digestion. practice of feeding young children with solid food, is the cause of great destruction of life; and even sops should only be sparingly administered, in cases of necessity, till the first teeth have appeared. The From what we have before said, it will be seen that in the adult man there [are thirty-two teeth, but if we examine the jaw of a child after it has "cut" all its teeth, and before it is six years old, we shall find that it has but twenty teeth; nor are these teeth increased in number by the addition of others; but, whilst this first set of teeth are performing their duties, an entirely new set is growing underneath them, in precisely the same way as they did at first. Gradually the fangs of the first set of teeth are absorbed in consequence of the pressure of those beneath, and they fall out, or are easily removed, and make way for the others. The order in which the teeth appear-as well as the time-is subject to considerable deviations, but the following periods will be found to be about the time. may be cut by the end of the third year, whilst, in others, the process of dentition may be prolonged to the fifth year. becomes decayed, so great pain is expe- · rienced. It will also indicate how it is that by the removal of a decayed part, and stopping it with some kind of cement, that Order of appearance of the permanent Teeth. access to the air is prevented, and the The internal structure of the teeth is very complicated, and has recently formed the subject of very profound research amongst the anatomists and physiologists of Europe. The minute structure is found to be no less indicative of the species of animal to which it belongs, than the whole tooth itself; so that with regard to the teeth we may say, that a morsel so small as not to be distinguished with the naked eye, should yet enable the skilful anatomist to judge of the form of the whole tooth, and thence to infer the particular kind of animal to which it belonged. We cannot go into the details of the dental structure of the lower animals, but all that possess true teeth exhibit the same facts as we find in man. If we make a vertical section of a tooth (Fig. 7) with a fine saw, and, after having polished it on a hard and smooth whetstone, submit it to an examination under the microscope, we shall easily make out the parts indicated in Fig. 7. We shall discover that there are three very distinct portions. First, the enamel (Fig. 7, a), which covers the whole of the external part of the tooth; second, the dentine (b) this substance, which is so largely developed in the tusks of the elephant and other pachydermatous animals, constitutes ivory; third, the cement (c) or bone, forming the external covering or facing of the tooth. In the middle of the tooth (d) is the pulp cavity. Into this cavity the nerves and blood-vessels of the tooth penetrate, and thus serve to maintain the living connexion between the tooth and the rest of the body. The distribution of the nerve (e) in this cavity (Fig. 6) will serve to explain how it is, that when any portion of the tooth danger of further decay removed. Each hard part of the tooth is differently formed. The enamel is by far the hardest of these structures, and is composed of dense semi-transparent fibres placed side by side, and so small, that they do not measure more than 300 part of an inch in diameter. These little fibres penetrate the dentine beneath. This substance is composed of two parts, viz., a number of very minute tubes anastomosing with each other, and an intertubular tissue. The tubes commence in the pulp-cavity, and pass on to the outside of the tooth. The intertubular substance is composed of very minute white granules or globules. The cement which covers the outside of the fang, has a structure precisely like that of ordinary bone. These substances are not always distributed in the teeth of the lower animals as they are in man. In the gnawing animals, for instance, the enamel is only on the front of the teeth, whilst the dentine is exposed on the back of the tooth. The consequence of this arrangement is, that the dentine, wearing up much quicker than the enamel, the latter is always left with a sharp edge. Those who know the history of agricultural implements will recollect that the very principle is involved here which has been so successfully applied to the making of ploughshares, by having one side of soft iron and the other of steel, and which has led to the formation of one of the largest manufacturing establishments in the east of England. The same principle is acted on in the formation of the elephant's tooth, in which plates of enamel are inserted crosswise through the teeth, and these are separated by dentine and cement. The more rapid wear of the dentine and cement keeps the enamel of the tooth constantly projecting, and thus secures a roughened surface for the more effectual trituration of the coarse food of these animals. The teeth are inserted in, or rather, developed out of, the upper and lower jaws. The upper jaw is fixed, but the lower jaw has two round projections, which are inserted into cavities in the skull, in which they move with great facility. This movement is different in different animals. In those creatures which feed upon vegetable fibre, as it exists in the leaves and branches of plants, the jaw admits of a lateral motion, and the trituration and reduction of this kind of food is thus ensured. On the other hand, in animals which partake of food that requires no bruising before it is carried into the stomach, this lateral movement would be of no use; hence in the carnivora we find this action of the jaw confined to a simple Fig. 7. up-and-down movement, by which the food is merely divided or cut into smaller pieces. When we examine the jaw of the human being, we find that it has a combination of these two movements-that it combines the rotatory action of the ruminant with the up-and-down movement of the carnivora. In the course of our remarks we shall have to speak more particularly of the nature of the food of man; but we would here point out, that in the structure of the jaws and teeth, we find a clear indication that he is adapted for taking food from both the vegetable and the animal kingdom, seeing that in the organs which prepare the food for digestion, we find instruments adapted for the preparation of both forms of diet. This is but one of many arguments that may be brought against the advocates of an entire animal or vegetable diet; and had we not such abundant proof in the structure of man, we might appeal to his instincts, which, under all natural circumstances, have dictated to him a mixed diet as that which is most desirable for his sustenance. Having said thus much with regard to the teeth, we conclude with a few directions as to their use, and the keeping them in integrity. In the first place, then, it is evident that the teeth of men are only adapted for dividing and triturating flesh and vegetables; and the delicacy of their structure would seem to indicate that even these forms of food should be cooked. The teeth of man neither possess the sharpness and strength of those of the lion, nor the broad surface of those of the ox or the elephant. The attempt to masticate hard substances -to crack nuts, or in any other manner to strain the strength of the teeth and jaws— is injurious; and many persons have to regret all their lives foolish practices of this kind. In the next place, the teeth should be regular. The want of harmony between the upper and lower teeth is sometimes so great, that the food is only imperfectly masticated. In the lower animals, occasionally, one tooth is lost, when its opponent grows to a length that is injurious to the animal. This is especially the case in the rodents; and sometimes the teeth, from this cause, grow so long, as to penetrate the parts of the face beyond the jaw. The irregularity of teeth produces an accumulation of tartar at their base, which causes an absorption of the gum, and eventually the tooth drops out without decay. These irregularities arise from inattention to the teeth during second dentition; but if proper care is taken at that period, all undue growth may be guarded against. The teeth should be kept clean. There are two sources of impurity to the teeth. The first is from a deposit of tartar upon them near the gum; and the second is from portions of food adhering to them after meals. The accumulation of tartar is a frequent source of disease in the teeth and gums, and precautions should be taken to prevent its adherence to them. The best plan is that of cleaning them with the brush night and morning. Dentifrices are frequently employed, and, perhaps, when simple, they are of service. All chemical products, however, should be avoided. Anything which acts chemically upon the tooth, will open the way to speedy decay. The simplest dentifrice, and one of the best, is a mixture of prepared chalk and well-powdered camphor. The chalk acts as a scouring material, whilst the camphor stimulates the gums, and counteracts the decomposition of any small particles of food |