3*2 



BEAVER. 



less action than the enamel ; and thus the enamel 

 always stands highest, and forms a cutting edge, while 

 the bone supports it behind like the basil or sloping 

 edge of a tool. Thus the cutting tooth of the beaver 

 is a chisel, and whether the carpenter's chisel has 

 been made in imitation of it or not, the same arrange- 

 of iron and steel as there is of bone and enamel in 

 the tooth, is the best possible for a chisel of all work. 

 There is one property in the chisel of the beaver, 

 however, which no art of man can give to the chisel 

 of the carpenter ; the incisive or chisel teeth in the 

 beaver have not roots consisting wholly of bone, as 

 in the teeth of most animals, and as in the grinders 

 of the beaver itself. They are inserted deeply in 

 the jaws ; but they are inserted in a peculiar kind of 

 socket a socket which exists only during dentition 

 in other teeth. These sockets continue gradually to 

 produce the tooth in such a manner as that both 

 bone and enamel grow at the root as fast as they are 

 worn down at the point ; and consequently those 

 chisel teeth remain in good condition during the 

 whole life of the animal. Their chisel edges are 

 directly opposed to each other, so that when the 

 animal bites, it bites clean, just in the same manner 

 as a workman cuts a wire or other small piece of 

 metal, with his cutting pincers. If by any means a 

 beaver loses one of those teeth, the opposite one in 

 the other jaw, having nothing to act against, is not 

 worn down, but continues growing till the point of it 

 j> rejects beyond the mouth, and the animal bites less 

 effectively than if that one had been removed as well 

 as its opponent. 



As is the case in all the rodentia, beavers have no 

 canine teeth. Such teeth would not only, from the 

 nature of their food, be perfectly useless to them, but 

 would be in the way of the cutting teeth, and prevent 

 them from acting properly. The grinders are four 

 in each side of both jaws, flat on the crowns, and 

 adapted for masticating vegetable substances. They 

 are, indeed, better adapted for this purpose than the 

 grinders of most of even this order, being marked 

 with projecting ridges of enamel, which can divide 

 substances of almost ligneous texture. Of these 

 ridges or folds, there are four on the crown of each 

 tooth ; but they are differently arranged in the two 

 jaws. Those of the upper jaw have three folds on 

 their outer surfaces and one on their inner, and those 

 in the lower jaw have one on the outer, and three on 

 the inner ; by this means the bark and other dry 

 and rigid vegetable substances which the animal 

 masticates preparatory for the stomach, are broken 

 at the middle of the tooth, and reduced to smaller 

 portions at each edge. The jaws have no lateral 

 motion upon each other ; so that the action of the 

 cheek teeth upon the food, more resembles that of a 

 bark-mill than the ordinary grinding motion in rumi- 

 nant animals. These cheek or grinding teeth have 

 proper roots, and not the same kind of socket as the 

 front teeth, so that they do not increase by growth 

 at the roots, as they wear down by using at the crowns. 



In the different modes of structure and growth of 

 the two sets of teeth in these animals, we have a 

 striking instance of the economy which is displayed 

 in the structural adaptations of nature. The cutting 

 teeth have not only the severest labour to perform 

 in the finding of the food ; they have various other 

 functions : they cut the wood, the bark of which is 

 to be the winter store, and also that which is to be 

 used in the construction of the dam or the hut ; and, 



in the performance of these operations, they have a 

 harder task than the teeth ot most animals. The 

 cheek teeth though they have to grind harder food 

 than those of most of the mammalia, have slight labour 

 as compared with the cutting teeth ; and thus, while 

 the latter are in constant growth, the former attain 

 their full size in the usual manner, and afterwards 

 grow no more. Thus, in the beaver, where the extra- 

 ordinary work has to be performed, we have the 

 extraordinary instrument for the performance of it, 

 and in that part where there is no extraordinary 

 work, the instrument follows the ordinary law ; only 

 the structure of the coronal surfaces of the grinding 

 teeth, is, as has been said, adapted for dividing sub- 

 stances approaching to the nature of wood, rather 

 than succulent or soft vegetable matters. 



And this is a general law in nature, and one which 

 most clearly establishes not only a purpose, and by 

 consequence a Maker, in all that nature displays; 

 but it shows that, anterior to creation itself, that 

 Maker must have known intimately, in itself and in 

 its connexion, every property of every substance, 

 every law of every combination, and every principle 

 of every science, mechanical, chemical, or whatever 

 else. Nay more, that the properties, the laws and 

 the principles must have emanated from that Maker, 

 and from Him alone ; and that all which the most 

 learned and the most studious of the human race can 

 know of any of those subjects, or of any part of them, 

 is not originally of human invention or human skill ; 

 but the humble and simple discovery of that which 

 God has ordained, and bearing probably no more 

 proportion to the knowable part of the whole than a 

 single dew drop of the grass bears to the congregated 

 waters of the Ocean. Then, though we could carry 

 our knowledge to the full measure of this science- 

 the science which being perceived by material organs 

 of sense, must be in itself material, there remains 

 behind a portion of the system far mightier in its 

 extent, and more wonderful in its operation the law 

 of life that mighty mandate which is one and con- 

 tinuous, yet varied as the races of being, and the ages 

 at which they live nay, as the individuals of those 

 races, and as those small moments of their existence, 

 which no sense or instrument can measure. 



To this portion of the subject, into which it is not 

 given to mortal eyes to look, the mind can contem- 

 plate only an infinitude in every part, or so to express 

 that to which no tongue of man is equal, an infini- 

 tude of infinitudes in the whole; a reflected but 

 express image of the Omniscient and Almighty 

 Maker and Governor. 



Nor, when we come even to the details, do we 

 fail to find proofs of this. Every power of life, con- 

 sidered in itself, and without reference to the quantity 

 of material substance on which it acts, is, to our com- 

 prehension, infinite in its power; and, as we have 

 had occasion to state again and again in the course 

 of this work, there is not a living energy recorded 

 within the whole volume of nature's book but which, 

 if it had full scope for its working, would in brief 

 space replenish the earth with its own species ; and 

 it would be easy to demonstrate, upon principles the 

 best known and the least liable to mistake or fallacy, 

 that in some species (as, for instance, in the common 

 cod-fish) this energy, originating in a single pair, 

 could turn, in half the average period of human life, 

 as much matter as there is in the sun and all the 

 planets into that species of fish. 



