The spring, early summer and fall are the most suitable seasons for castrating the young. It may be practised during the hot or cold months of the year with little danger from wound infection or other complications, providing the necessary after-attention can be given. _The preparation of the animal_ for the operation by withholding all feed for about twelve hours is very advisable. If this is practised, the stomach and intestines are not distended with feed, and the young are cleaner, easier to handle and suffer less from castration. Clean quarters and surroundings are very necessary to the success of the operation. _The instruments required_ are sharp knives, preferably a heavy scalpel and a probe-pointed bistoury, an emasculator for large and mature animals, and surgeon's needles and suture material. Ropes and casting harness are frequently used for confining and casting the large and mature animals. Two clean pans or pails filled with a two per cent water solution of liquor cresolis compositus, or an equally reliable disinfectant, should be provided for cleaning the scrotum and neighboring parts and the instruments. Pieces of absorbent cotton or oakum may be used in washing and cleaning the scrotum. The instruments should be sterilized in boiling water before using. _If a number of pigs or lambs_ are to be castrated, it is best to confine them in a small, clean, well-bedded pen. This enables the attendant to catch them quickly and without unnecessary excitement or exercise. They should be taken to an adjoining pen to be castrated. The scrotum should be washed with the disinfectant, and the testicles pressed tightly against the scrotal wall. An incision parallel with the middle line or raphe and a little to one side is made through the skin and the coverings of the testicle, and the testicle pressed out through the incision. The testicle and cords are then pulled well out and the cord broken off with a quick jerk and twist, or scraped off with a knife. The latter method is to be preferred in large lambs if the operator does not have an emasculator. The incision in the scrotum should be extended from its base to the lowest part, in order to secure perfect drainage. _Young calves_ may be castrated in the standing position or when cast and held on the side. The method of operating is the same as recommended for pigs and lambs. _The castration of the colt_ may be performed in either the standing position or when cast. The method of operating is the same as practised in the smaller animals with the exception of cutting off the cord. The emasculator is used here. This instrument crushes the stump of the cord and prevents haemorrhage from the cut ends of the blood-vessels. Careful aseptic precautions must be observed in operating on colts, as they are very susceptible to wound infection and peritonitis.