Any considerable =change of the conditions of life= may operate in the same way. A sale and transport to a distance with change of feed, water, work, stabling and even of climate is at times a potent factor. Prietsch has seen a horse attacked three times in a single year, and on each occasion after a change of ownership and locality. Trasbot quotes an Algerian veterinarian to the effect that many of the percheron horses imported into the Mitidja are attacked by encephalo-meningitis during the extreme heats of summer. A careful observation of cases will however show that in the majority of cases an attack comes not from one individual factor alone but from a concurrence of several operating together. Other cases are caused by =embolisms= and =infections= from diseases localized in other parts of the body. Thus we have cerebral abscess in pyæmia, strangles and omphalitis, and cerebral congestions and inflammation in canine distemper, equine contagious pneumonia, laminitis, and angina. Among mineral poisons, =lead= is notorious as a cause of acute cerebral disorder often leading to inflammation. Other mineral poisons like =arsenic= and =phosphorus= may lead to encephalitis symptomatic of gastro intestinal irritation, or caused by the toxic products of indigestion. Rapidly growing =tumors=, like cholesteatomata, are liable to induce recurrent attacks of encephalitis in connection with periodic irritation. Finally =parasites= in the cranium are sufficient causes of attacks. In the New York State Veterinary College Museum is the brain of a cat with a nematoid wound round the hypophysis. In equine subjects suffering from the strongylus armatus the larval worm or clots caused by its presence in other arteries sometimes invade the encephalic blood vessels causing disturbances of the circulation, embolism, inflammation or degeneration. (Albrecht, Von Heill). The larvæ of the œstrus has also been found in the brain substance producing inflammatory or degenerative foci (Brückmüller, Megnin, Siedamgrotzky). Their presence in the nasal sinuses at times cause encephalitis by contiguity. The cestoid worms, cœnurus in sheep and other ruminants, and cysticercus in swine, find their natural larval habitat in the brain and by their movements produce more or less congestion and inflammation. Cases of cœnurus in the horse have been described by Rousset, Frenzel, Zundel, and Schwanefeldt.