Ferrets are rather difficult animals to raise in numbers--it requires a large amount of patience, great care, and scrupulous neatness, although when full grown they are very hardy. The writer's ferret breeding grounds consist of special farms, on which are erected numbers of small barn-like structures, each furnished inside with a dozen pens, and an aisle running through the middle. Every pen is as large as a horse's stall, the boarding and other accessories are kept clean by vigorous scrubbing, the sawdust on the floor is changed once a day, and the pens and the ferrets are otherwise attended by experienced ferret men. Here the ferrets are taught to do their work of killing and hunting by practical experiment on live rats. Although it is in the nature of ferrets to hunt and kill rats, the same as it is for a bird to fly, yet we find a little extra course of training is necessary in both cases. It will not do to hunt with ferrets until they are at least seven months old. Ferrets breed but once a year, and have from four to nine at a litter on the average--it is very rarely they have two litters a year. They are trained to the whistle by feeding them every time this instrument is used, so that after awhile they promptly respond. The ferret is ruled through his stomach. The time of the ferret's getting in heat is in March, nine weeks after which they breed. The male invariably takes hold of the female as if he were going to strangle her. The young are born without hair, and must, therefore, be kept warm. They have their eyes open in thirty days, and should be fed on as much milk as they want.[A] The male should be removed from the female before the littering, the symptoms of which are exactly like a cat or a dog, or else he will destroy the entire brood. Care should be taken to have the female well supplied with food during the period of copulation, or else she may casually munch up the young herself, and the writer has lost many a pretty litter by this little habit of the unnatural mother. As in crops, there are years for raising ferrets which are more fortunate than others, some seasons having a fatal effect on the young ones. [A] They ought not to be handled before they are one month old. IX.--STRENGTH AND BITE. The great strength of the ferret is in the teeth, neck, and forefeet. One ferret can hold up eight times its own weight with its teeth. Twenty or thirty ferrets when hungry will fasten their teeth in a piece of meat and can be picked up in this way and swung around without ever causing them to think of letting go. They will hang to an object which they have been provoked against with a persistence which would make a Bill Sykes bull-dog blush with shame. The only way to loosen their hold is to grasp them firmly around the neck with the pressure on the skull, and to shove them _towards_ the object, not _from_ it, for if you try the latter way you can pull for a day and a night without any perceptible result on the ferret.