Sunlight, to the extent which we experience it in England, has a direct and an indirect influence for good on the health of horses. In human beings it apparently improves the quality of the blood, seemingly by its action on the red corpuscles. The "sun cure" has therefore been prescribed with more or less success for various diseases of mankind. From experience, I think we may safely assume that sunlight directly promotes the health of horses; supposing that its intensity is not tropical. Respecting its indirect action as a destroyer of disease germs there can be no doubt. Thus, Arloing tells us that sunlight impedes the growth of the bacilli of anthrax; Hewlett states that direct sunlight destroys the bacilli of tetanus in from fifteen to eighteen hours; and Sherrington mentions that the microbes of glanders are killed by sunlight in about three days. It is supposed that this action of sunlight is due to the fact of its giving rise to the formation of ozone or peroxide of hydrogen, both of which are germ destroyers.