perience. Arrival at the adult period is determined by certain indications sufficiently definite to be universally recognized, and to remove all difficulty about the time of its occurrence, the animal is fully grown, the permanent dentition is complete, and all the physical qualities are perfect. At this period the assimilative functions seem to lose some of their activity; and the deposition of new materials under perfectly healthy conditions is about equal to the waste of the tissues, preserving something like uniformity of size for a time: as age advances nutrition becomes still less active, and often less material is deposited than suffices to supply the waste, and a decrease in bulk is the result. This, however, being influenced by various circumstances, is not an invariable consequence.

Natural development presupposes a healthy condition of system, sufficient food, and the full exercise of every organ: such conditions, in fact, as ordinarily exist in nature. In association with these favorable circumstances there will be others of an opposite tendency, whose operation, however paradoxical it may appear, is conducive to the desired result. In the discussion of these opposing influences we shall find much that is of prac tical value.

DEVELOPMENT OF THE ANIMAL UNDER NATURAL CONDITIONS.

In the wild state, where domestication has no influence, and man's interference is not felt, the conditions of existence are very materially different from those which are artificially established. Weak and diseased animals are placed in the most unfavorable position. Where healthy animals owe their preservation to their capabilities of flight, the maimed have slight chance to escape destruction; and, in general terms, where full vigor of all the animal faculties is indispensable to the preservation of existence there is present a natural and constantly-operating agency for the destruction of defective animals, who, under other conditions, might exist and perpetuate their defects.

On this grand principle depend all the essential differences between the natural and artificial conditions of life. In nature there is a guarantee in some considerable degree for healthy development; while under domestication much is left to be determined by judgment or caprice. Naturally, therefore, we may conclude that a healthy state of the organism will, as a rule, characterise the majority of animals under natural circumstances.

As the conditions of existence influence the animal's qualifications and tendencies, we may still further conclude with safety that there will be a proper exercise of all those capacities, which become more developed as they are more actively employed. In this way the strongest and most perfeet animals enjoy the largest share of the advantages of their position,

while the weakly ones are most affected by destructive agencies, such as inclemency of season, scarcity of food, and predatory attacks from larger animals.

It is not contended that an entire exemption from injury or disease is a condition of the natural state of existence. Animals suffer from accidents of various kinds, and are commonly found affected with disease; but it is most important to observe that any radical defects are not likely to be perpetuated, because the circumstances under which the animal is placed lead to his destruction so soon as he ceases to possess the qualifications necessary for resisting the adverse influences by which he is surrounded. It is scarcely necessary to illustrate this statement, although numberless instances at once present themselves. An animal whose freedom of movement is interfered with becomes an easy prey to his pursuer, while the predatory beasts under like circumstances are incapable of providing food for hemselves.

Radical defects, it is apparent, can only be extended to a certain point, and that not a very remote one; for the reason that their general extension would diminish, and ultimately exterminate the race, by depriving it of the qualities on which its existence depends.

Every animal in a state of nature has to seek its own food, and in so doing preserves the due proportion between the waste and reparation of his tissues. The food on which he subsists, again, contains in natural combination the elements which he requires, and which his organs are capable of appropriating. Certain portions are devoted to the support of his fresh, while other parts furnish the necessary supply of fat; any excessive accumulation of one or the other being prevented by the healthy activity of the excretory organs. By exertion, by respiration, by exhalation from the skin, by secretions from the liver and kidneys, the old and worn-out materials are removed, and by digestion of the elements taken by the animal as food new materials are prepared, and in the course of the circulation of the blood deposited to compensate for the waste. So long as all these conditions continue in perfection, so long as the old materials are removed and the functions are all active, and the animal obtains a due supply of proper food, it is difficult to realize the possibility of the occurrence of disease, except from the action of some violent mechanical or chemical

cause.

During the growth of the tissues many circumstances influence the development of particular parts. In animals whose mode of existence necessitates speed, for pursuit or flight, the respiratory organs, with the organs of progression, will indicate the possession of the capability; the habit of rapid movement naturally leading to a preponderance of those parts which

are most necessary for the perfection of the quality; under the same circumstances the circulation will be very active, and hence the organs in this system will be proportionately developed. Activity of respiration, circulation, motion, and secretion, are opposed to excessive accumulation of tissue, particularly of fatty tissue, as well as to great bulk of body. It is merely begging the whole question to say that these things are denied the animal because they would encumber his movements; they are absent because the habits of his life occasion the development of organs whose healthy exercise is opposed to such accumulations; quick movement, active respiration and excretion being destructive actions, are of necessity incompatible with excessive deposition.

Domestication essentially modifies the conditions of existence, the change being in exact proportion to the difference of the animal's previous habits, as compared with his present mode of life. How decided the variation really is will be apparent upon a very cursory review of the new circumstances under which he is placed.

DEVELOPMENT OF THE ANIMAL UNDER ARTIFICIAL CONDITIONS IN A STATE OF DOMESTICATION.

Instinct, which guides the wild animal in the choice and pursuit of his food, and volition, which regulates his movements, are alike rendered powerless by the new conditions of his existence. It is no longer for him to determine when he will seek provender, or what kind of aliment he will select. A superior will is substituted for his own, and he has now no choice but to eat and drink, more or less, according to his possessor's judg

ment.

Seldom, in thinking upon the differences between the wild state and domestication, do we quite realize the change in its completeness; how entirely in nearly every particular the circumstances are altered. The animal's character may remain the same, but his power of action, his individuality, is lost; if he has been accustomed to depend for his food upon his bodily strength and activity, he is now to remain quiescent until supplied with what is deemed necessary for his sustenence; if formerly he was in a state of ceaseless motion, he must now rest until permitted to move. Scarcely one of his qualities can now be spontaneously displayed.

Of the positive influence of the artificial system of treatment no more satisfactory evidence can be adduced than is afforded by the changes observed in the development of the teeth of the domesticated breeds as compared with the production of those organs in animals placed under more natural conditions.

M. Gerard, in his work upon the teeth, places the completion of permanent dentition in the ox at four-and-a-half to five years; that of the sheep from four to four-and-a-half years; of pigs, two and two-and-a-half years. That his statements are founded upon observation no one will doubt who considers his professional position. As early as 1846 the occurrence of a remarkable case on the Continent excited considerable attention. In 'The Veterinarian' for 1847, M. Renault comments upon this case in a letter dated August, 1846. After remarking on the importance of admitting the influence of early feeding and careful selection of breed upon the dentition, he adduces the instance of a certain bull (Antinous) who, at an adjudication, extorted universal admiration on account of his fine quality, but was refused the prize on the ground that the conditions specified that the candidate should be but two years of age, whereas the animal, from the condition of his teeth, was four years old and upwards, and the opinion was corroborated by several veterinarians, who all certified the bull to possess all his permanent teeth. Ultimately satisfactory evidence was given that the animal was really no more than two years old. M. Renault commenced a series of inquiries upon the point in question, stating his conclusions as follows:

"Uniformly where the ox species has experienced the ordinary kind of management and feeding, wherever food, however good, has been given as ordinary nutriment, and not for forcing or fattening; in all such parts of the country dentition follows the ordinary course, as indicated by writers on the subject.

"But these rules, the result of long and accurate observation, and correct and well founded at the time when and in the countries where they were made, are no longer applicable and true in regard to certain individuals and certain breeds.

"Indeed, thanks to a better system of management and feeding of cattle, and to judicious and advantageous crossings, it is certain that for some years past many of our bovine races have experienced in their form, and especially in their precocity of development, unmistakable amelioration.

"Whatever may be the cause of this remarkable aptitude in certain breeds to acquire their growth early, it is readily conceivable that such precocious development can not be confined to any particular organs. If every one has not equally participated in it, at least they are all more or less affected by it. Above all, the digestive system-the part called in to play an important part in the preparation of such aptitude, since all must essentially result from the nature and action of alimentation-must be one of the first to undergo important modifications.

"Physiologically, therefore, it may be argued, we must admit that the

use of teeth and dentition ought to be earlier in subjects weaned at so early an age, and so soon fed with substantial food."

Nearly twenty years have passed since these observations were made, and animals have continued to progress in their aptitude to fatten, and their precocity of development, as witness some of our best horses and oxen at two years old, sheep at one year, and pigs at six months.

DOMESTICATION NOT ONLY MODIFIES THE CONDITIONS OF DEVELOPMENT, BUT IT EFFECTS IMPORTANT ALTERATIONS IN CIRCUMSTANCES UNDER WHICH DISEASE IS PRODUCED AND EXTENDED FROM ONE GENERATION TO ANOTHER.

Disease in the wild animal finds its limitation in the general probability of the subject falling a victim to the numerous adverse influences, which he is incapable of combating. In domestication these adverse influences lose much of their power, or are sensibly modified by the institution of measures intended to combat their effects. Defects, which in a natural state would render the animal incapable of living, and which, if perpetuated, would ultimately lead to the extinction of the race, are, under the new conditions, fostered and extended, and take the name of "hereditary" or "transmitted" diseases, running through whole generations, or occasionally ceasing for a time only to burst out again with renewed violence.

It would be doubtless a reproach to our humanity if the weaker animals did not receive more care and consideration than the stronger; but who fails to comprehend that this course of procedure, the opposite of what is true in nature, must ultimately be injurious to the race, however conscientious we may be in adopting it? Singularly enough the details of the natural system which often are harsh, even relentlessly cruel, in our estimation, tend to the universal progress; while our efforts, dictated by humane consideration and undeniably productive of immediate individual or limited good, have often the tendency to produce universal deterioration.

Wild animals will not be expected to improve under the treatment they meet with in domestication at the commencement; not until they have become perfectly habituated to the new mode of existence are they likely to accommodate themselves to the change. The time required to effect this will vary, but several generations must pass before the wild original progressively passes into the domesticated animal, who now possesses so few of his native qualities as to be incapable of existing under conditions which were formerly essential to the continuance of his race.