Another form almost universally prevalent in this district of central New York in 1889 broke out on the teats and udders as blisters strongly resembling cowpox, but which were not propagated when inoculated on calves. It was only exceptionally that this extended through the teat to the gland tissue, yet in some instances the bag was lost from this cause. Scarlatina in man was very prevalent at the time (many schools were closed in consequence), but no definite connection seemed to exist between this and the cow disease, and on different dairy farms there were families of young children that had never had scarlet fever and who did not at that time contract it. The most common cause of contagious mammitis in cattle is a spherical bacterium in chain form (_Streptococcus_) (Moore, Ward). Yet it is clear that contagious mammitis is not a single affection, but a group of diseases which have this in common, that they attack the udder. _Prevention._--Prevention is to be especially sought in all such cases. In purchasing new cows see that they come from a herd where the teats and udder are sound. If a new cow with unknown antecedents comes from a public market, let her be milked for a week by a person who does not milk any other cows. Keep her in a separate stall from others, so that there may be no infection from litter or flooring. Wash the udder with soap and water, and wet with a solution of two teaspoonfuls of carbolic acid in a pint of water before letting the regular milker of the other cows take her. If any cow in the herd shows the indurated end of the teat or the inflammation and nodular tender character of the gland, sequestrate her at once and give her a separate milker. If another cow is to be put into the stall she occupied, first clean and scrape it, and wet it with a strong solution of bluestone, 5 ounces in a gallon of water. The milk may be drawn off with a teat tube, or spring teat dilator (Pl. XXIV, figs. 3 and 4), and the milk ducts injected frequently with a solution of peroxid of hydrogen or iodoform. I have had little success in checking the upward progress of the disease through the teat with carbolic acid or boric-acid solutions. Used on the outside of the other teats, however, they may serve to prevent them from becoming infected. In the absence of peroxid of hydrogen the affected teat may be injected with a solution of 1 grain corrosive sublimate in a pint of water, and the same may be used on the other teats, provided it is washed off every time before milking.