Lecoq and Loiset in their investigations regarding this disease in colts mentioned the almost invariable existence of lesions in the umbilical region. Bollinger in 1869 recognised the possibility of infection by way of the umbilical vein. Röll and Guillebeau are of the same opinion, and Morot’s excellent study shows that here must be sought the most frequent point of origin of the articular symptoms. In animals born in dirty stables the umbilical cord becomes infected at the time of birth, or its cicatrix a few days later. The result is the development of rapidly fatal septicæmia, suppuration in the wound, omphalitis, omphalo-phlebitis, or umbilical arteritis; and to this infection are due the various complications, which may appear almost immediately, as in the case of septicæmia of calves, or may be deferred for a shorter or longer interval, for so long indeed that the umbilicus may appear to have healed externally (infectious pneumonia and endocarditis, infectious arthritis, etc.). The umbilical cord and the tissues surrounding the cicatrix form excellent culture grounds for those microorganisms which always exist in such abundance in litter and manure; and there is, therefore, no difficulty in understanding why in dirty stables infection so readily occurs. The infective agents may be of very varying kinds, a fact which explains the difference in the symptoms which follow umbilical infection; although ovoid bacteria, streptococcus pyogenes, and the bacilli of necrosis seem most common. Omphalitis and omphalo-phlebitis are not the only diseases capable of producing infectious rheumatism in young animals. Certain infections resembling dysentery and diarrhœic enteritis are also its frequent forerunners. In young animals even rachitis, which is accompanied by various digestive disorders, may serve as the point of origin for infectious rheumatism and all its complications. In older animals—_i.e._, in animals from five to six months, or even twelve to fifteen months—infectious rheumatism may occur without a clearly defined cause. It then develops with the symptoms and lesions of that condition known as “osteomyelitis of adolescence” in human pathology. These forms of osteomyelitis are due to infection with streptococci and staphylococci. In veterinary medicine the pathogeny has not yet been accurately ascertained. =Symptoms.= Infectious rheumatism in young animals assumes one of two clinical appearances, possibly due to different causes, viz.—plastic or suppurative arthritis following umbilical infection, and simple exudative arthritis. In the former variety symptoms appear soon after birth, rarely after the age of two months, and as an exception in animals of six to eight months affected with rachitis. The onset is sometimes sudden; the patient, though healthy on the previous evening, is unable next morning to rise or move. Hence in France this disease has received the titles, amongst others, of laminitis and paralysis of the newly born.