_Genus and Breed. Milking Capacity._ This is essentially a disease of cows, probably largely because of all domestic animals, cows only have been long and systematically bred to secure the greatest power of digestion and assimilation and the highest yield of milk. It is the disease not only of cows, but of milking breeds, and preëminently of individuals that give the most abundant dairy product. It is rare or unknown in scrub or common herds, while common and fatal in the best milking breeds, in advancing ratio about as follows: short horn, red polled, Normand, Swiss, Ayrshire, Flemish, Dutch, Alderney, Jersey, Guernsey, and Holstein. Heredity may be claimed, as the special predisposing qualities are hereditary. _Age_ has a marked influence, but this is subsidiary to the milking qualities. The disease rarely attacks a cow after the first or second calving when the system is as yet immature, and the milk yield has not reached its maximum: nor one that is past its prime and already failing in vital energy and milking qualities. The following table is from statistics compiled from veterinary records in Denmark and Bavaria: Age, yrs Cases —3 —8 4 21 5 65 6 160 7 171 8 202 9 117 10 124 11 44 12 70 13 78 and over. It will be noted that it is in the period of the most vigorous, mature life, from the 6th to the 10th year inclusive that the great majority suffer. In a judiciously managed dairy it is the best cows that are carried at these ages, and although the very best are kept on into old age they show a steadily decreasing number of cases as they begin to fail. The disease is all but unknown in primipara. _High Feeding._ Heavy and rich feeding prior to calving and immediately after, is a most prominent cause of the affection. This is so well known to owners of milking breeds, that they usually hold to the principle that the cow that is a heavy milker, should be all but starved for a fortnight before calving and for a week after. In herds where this rule is acted on the disease is rare and may be altogether unknown, and when it is neglected the malady is often very destructive.