The principles upon which Darwin based his theory of evolution—which are now accepted by scientists the world over as biological laws—are the very same as those under which the dog breeder works. Modern animal breeding is evolution in which man plays Dame Nature's part.

Breeding is, however, far from being an exact science, though it is continually becoming more and more scientific in its methods. We cannot sit down, a pencil in our fingers and paper before us, and with the aid of the stud book and a set of mathematical formulas figure out a dog that will surely be a champion. We can, however, with a knowledge of the scientific data that biologists have collected in their research work supplementing the lore and traditions of the kennels, come nearer and nearer to the breeder's ideal of "a champion in every litter."

It is quite obvious that with such plastic materials to work with we can never hope to have a perfectly uniform product, but who would have it so? Dog breeding is now more uncertain than roulette, twice as fascinating as the stock market, as interestingly exciting as auction bridge. Make it a matter of mathematically exact rules working out as invariably and regularly as a machine, and the charm has vanished.

The three principles of Darwin's idea of how and why evolution acts, are heredity, variation, and selection. The law of heredity says that like will produce like; that two Airedales will have Airedale puppies; two Scotties will have Scotties; two Irish terriers will have Irish terriers. The law of variation says that no two dogs, even if they be of the same litter, will ever be exactly alike even in the smallest details. No two St. Bernards were ever alike, nor were the smallest teeth of the two smallest Pomeranians ever identical. There is ample evidence to show that the chemical composition of the muscles, bones, and blood of different animals of the same species are different, and even vary considerably in one individual at different times. The law of selection is the law of the struggle for existence, the survival of the fittest. The three laws together make up the theory of evolution by means of natural selection.

What man does in breeding is the making and improving of species by artificial selection. He takes advantage of the law of heredity to establish breeds. If like always exactly reproduced like, however, that is as far as he could ever get, but because there is infinite variation, the offspring differ from their parents. By selecting those that come nearest his ideal, the breeder does just the same as Dame Nature when she kills off the unfit.

Since earliest times, man, more or less without thought or any knowledge of the whys and wherefores, has been carrying on scientific breeding in an unscientific way. Ever since he has kept domestic animals, his selection, formerly more or less unconscious, has been exerting its powerful force. For generations, the dog fanciers have been doing this: picking out the dogs and bitches most to their liking and mating them. The result is that while all breeds of dogs are closely enough related to inter-breed, still some are of comparative age and most breed wonderfully true to type.

Until quite recently, the dog breeders have been following the old, unscientific method, with some additional effort to correct faulty points in their dogs. That is, they have picked out individuals for breeding stock that came as near as possible to their ideals, and if the prospective mother was bad in head they selected a stud dog strong in this point; while a very good coated matron might be mated to a poor coated dog provided he possessed marked excellencies in other directions.

Unfortunately, but very scant attention was paid to the dams. This was largely from economical considerations, which led them to believing, or thinking they did merely because they wanted to, that "any old bitch with a pedigree was good enough to breed from." To bolster up their economy, they said that the pups inherited their looks from their sire and their dispositions from their dam.

Two changes have taken place in the past decade. Breeders now know that physically as well as mentally the dam is quite as important as the sire. Moreover, they have learned that individual characteristics, however marked they may appear to be, do not have the force of family traits. In other words, a short, thick headed bitch bred to the longest headed dog alive would have short headed pups, if that dog had short headed parents and grandparents. These two fundamental bits of knowledge, learned originally from the biologists, have had a big effect on breeding operations.

A logical outgrowth of the importance that has been placed on family, with the naturally lessened emphasis on the individual, has been an increased number of the devotees of line rather than in-breeding. In-breeding is beyond all doubt the strongest weapon the dog breeder has, but it is a boomerang that is very apt to come back and knock its thrower in the head. In-breeding is the breeding together of the blood of one dog—mother to son, or brother to sister. Line-breeding is the breeding together of dogs of the same general strain, comparable to second or third cousins among people.

These breeding experiments fix the good and bad points of a dog or a strain very strongly. Carried to an extreme, they result in bad constitutions, lack of gameness, and in extreme cases, in actual deformity. Such breeding demands that only the strongest and youngest dogs be mated.

In selecting a sire, one should pick out a dog of recognized breeding, whose ancestors were dogs of the type you desire. A winner and a son of winners has better chances of being a sire of winners than an unknown dog of doubtful family, but it is not always wise to rush to the latest champion. A popular bench hero is apt to be over-worked at stud. If your bitch is very young send her to an older dog and vice versa. Best results are not obtained if the dogs are over eight years old—that is a very good age limit at which to retire them from active service. A bitch may be bred at her first "heat," if she is not too young and is strong and healthy.

Most people know that a bitch comes in season, or is "in heat," fairly regularly at six months intervals, and that this is the only time when she will have any sexual connections with a dog. The terriers generally come into their first heat when eight or nine months old and are remarkable for the regularity of their periods. The first sign is a swelling of the external parts and bleeding. After a week or ten days the bleeding is followed by a thickish, white discharge. This is the time to breed her.

One service is all that is necessary—the old timers to the contrary notwithstanding. Two services were formerly given, but this is no longer done by the best breeders. The time of gestation is only sixty-three days, and the second service, two days after the first, has been suspected of destroying the effect of the former. Statistics show that there are fewer misses and just as many puppies when there is but one service, as when there are two.

The single service is obviously a great saving of the energies of the stud dog, who, if he be popular, has to make heavy demands on his vitality. One who places a dog at public stud assumes certain responsibilities,—the keeping of his dog in perfect health and attending most carefully to visiting matrons. The stud dog should have lots of exercise, all the water he wants, and an abundance of good food. Raw lean meat, chopped fine or run through a mechanical grinder, makes a fine supplementary diet, and raw eggs and a little sherry can be added to this if he becomes at all run down.

Visiting bitches must be guarded against all possible chance of a misalliance. If practical, they should be kept far off from the other kennel inmates, for quiet is something to be greatly desired for them. When they arrive, they should be given a run and drink, but do not feed them till they have quieted down a little from the excitement of the trip. The Golden Rule covers the care of these visitors like a blanket—just treat them as you would have a bitch of your own treated under the same circumstances.

When a bitch has returned to her home kennels, she should take the rest cure a day or so. After that for a month or six weeks she need be treated no differently from any of her kennel mates, save to see that she has plenty to eat and that her stomach and bowels are in perfect order.

When she begins to show signs of heavy whelp take her away from the others, and while her exercise wants to be kept up by long walks she should not be allowed to run or romp, or she may miscarry. Her box should be fixed a few days before the pups are to be born. Let it be large enough for her to stretch out in, but not big enough to give her room in which to move about, or she may kill or injure the pups by treading on them.

Once in a while one has a bitch who neglects her pups disgracefully, but the usual thing, in terriers at least, is over attention to the sacrifice of her own condition. A few bitches eat their newborn pups. Fear is the motive, but once done they seem to get the habit. Feeding quantities of raw meat just before they are to whelp is the best, but not a sure cure. Bad mothers, ones who walk on their babies, neglect them, or turn cannibal, are very rare among the terriers.

To return to the box: it should, as I have said, be just large enough to be comfortable. The best bedding for the whelping time is a bit of old carpet, to be substituted for straw when the family has safely arrived. A little shelf, about three inches from the bottom and two inches wide, tacked round the box will prove to be good puppy life insurance, for it keeps them from being pressed to death against the sides of the nest.

Terriers whelp better if left to themselves. It is the rarest thing for them to have any trouble, and if one will just keep a weather eye open to see that things are really going well, they will continue to go well without interference. The pups should be born inside two hour intervals, and if this limit be passed the mother needs attention. The drugs used, however, are so strong and so poisonous and an operation is so delicate that it is invariably better to call in the veterinarian's skilled aid.

After the puppies are all born the mother should be given a bowl of thin oatmeal gruel and left to herself. She will ordinarily clean up the nest herself, eating the after-births and licking the puppies clean. I have found that after she has cleaned a pup, which she does as soon as it is born, it is advisable to take it from her, wrap it in flannel to keep it warm and dry, and to wash off the navel cord with some mild disinfectant such as listerine, or a very dilute solution of bichloride of mercury or carbolic acid. Cold is fatal to very young puppies, and the navel cord is the source of a germ infection that kills many in the nest.

The dam, while nursing her family, must have an abundance of food—plenty of soups, gruels, meats, and milk, but not many vegetables, for they are full of water and waste. She needs more concentrated nourishment. When you think that you can fairly "see puppies grow," you can appreciate how great a drain there is on the mother. Because of this, it is never advisable to let a terrier attempt to raise more than five at the outside, and four is really better than five. If a foster cannot be obtained—very often the local pound will have a healthy mongrel which they will let you have for the license fee—it is kindness and economy to kill off the puppies in excess of four or five.

What ones to destroy is a delicate question. It is usually safe to discard the last one born, who is so often the runt of the family that he is known to kennel men and veterinarians as the "wreckling." It takes a very experienced eye to tell much about the points of a new born puppy, but two salient features to be remembered are that not once in a hundred times will a light eye get darker and any tendency to big ears is comparatively easy to spot and invariably gets worse. A good safe rule in terrier puppies is to save the ones with the longest, flattest heads, the heaviest, straightest fore legs, dark eyes, small ears, short bodies, taking these points in the order named, but discarding any pup who is glaringly off in any of these details.

The mother will wean the pups herself when they begin to grow their teeth, and it is best to leave this to nature. When their eyes are opened they should be taught to drink for themselves by sticking their noses in a saucer of sweetened milk. About the time they are fully weaned they should be treated for worms. After this first worming, they should have similar treatment every six weeks till they are six months old, and twice more after that before they are out of the puppy class. All dogs should be treated for worms twice a year as long as they live.

It is the style, or custom, or what you will, to cut the tails of Airedales, Irish, Welsh, and fox terrier puppies. This ought to be done when they are three or four days old. Three vertebrae are left, that is, the tail is cut at the third "knuckle," not counting the first one at the root of the tail. Rumor says that the operation is done with the kennelman's or groom's teeth, but in reality a dull pair of scissors is the usual and best instrument. The skin should be pulled back toward the body, so that there will be a little extra to cover the end, and not leave it bare of hair.

Growing pups need three things—food, room, and sunlight. When first weaned, they should be fed milk, gruels, and soups five times a day and the number of meals gradually lessened and the amount of solid food gradually increased till at a year old they are fed the same as their older kennel companions. The more room puppies have, the better they are. This is probably the reason that puppies farmed out always do so much better than those kennel raised. They may get all sorts of food and they certainly do not get the attention given the ones in the kennels, but a farm raised youngster is always healthier, bigger, and stronger.

Sunlight acts on puppies as it does on growing plants. Winter pups are proverbially more troublesome than those born in the spring. Most fanciers, therefore, see to it that their brood bitches whelp only in the spring. One litter a year is enough to ask of any terrier.

In conclusion, a word to the small kennel owner. He is apt to think things are unfairly distributed and that he has not the chance either in the show ring, the field, or the breeding kennel that the large owner has. In the latter two, and especially in the breeding kennel, he really has an advantage. It is well known that the greatest number of good dogs are bred by owners of from one to five bitches, for they study their needs more carefully and can give the puppies better attention. Let the small breeder but study his breed; know its past great dogs; understand the meaning of pedigrees; mate his bitches according to his knowledge; rear his puppies carefully, and he will find that he will turn out better home breds than ever come from the big kennels.