_Plethora. High Condition._ Heavy feeding and high condition usually go together, and the majority of the victims are fat or in good flesh, yet a certain number are actually thin. The predisposing condition is plethora rather than fat or flesh, and this may be present in the comparative absence of flesh. The cow that is from a stock famed as heavy milkers, does not tend to lay on flesh, but, on succulent diet especially, the greater part of the nutritive matter assimilated goes to the production of milk, and she remains thin in flesh no matter how heavily she may be fed. Many such cows never go dry, but give a liberal yield of milk up to the day of calving, and if measures are taken to dry them up, it is done at the expense of a sudden plethora, as the milk giving system does not at once accommodate itself to the laying up of fat and flesh. The _drying up of the milk secretion_ sometime before calving in a cow which is normally a heavy milker is therefore a potent factor. _Parturition_ is an almost indispensable factor as the disease occurs one to seven days after that act, and only in rare and somewhat doubtful cases before it. _Easy Delivery_ with little nervous outlay or loss of blood, and no exhaustion is a special feature. The attack almost never occurs after a difficult parturition with considerable loss of blood and much nervous exhaustion. This should to a large extent exclude such alleged factors as _shock_ or _wearing out of nervous energy_. The nervous prostration which figures so prominently in the disease, seems to be less the result of wear and tear, than of the supply of an excess of blood, which is either over-enriched, or charged with some injurious toxic matter. At the same time there is a manifest susceptibility at the parturient period which is not present at other times, and the plethora or toxin takes occasion to operate when this predisposition renders such an attack possible. _The Warm Summer Season_ has been claimed to induce a greater number of cases, and doubtless exposure to continuous heat, tends to prostrate the nervous system and predispose to congestion, this fails to take into account the still more important element of the rich spring and early summer pastures, where the already plethoric animal is left to feed without stint, or the tempting red clover, alfalfa and other fodder crops, rich in albuminoids, which are fed liberally in a succulent condition. _Chills in cold winter weather_ have been similarly invoked as driving the blood from the surface to collect in internal organs, including the brain. That chills do act in this way cannot be denied, but there is no demonstration that any number of cases have been materially affected by cold.