_Nervous System._—The organism seems to have a selective action on the nervous system as shown by headache, various neuralgias, insomnia, apathy and neurasthenia. Sciatica is probably the most common peripheral nerve involvement. _Joint Symptoms._—Very characteristic are the sudden and painful swellings of various joints, especially hip, shoulder, ankle and knee. Not rarely the costo-sternal articulations may be involved. The acute symptoms subside in a few hours and the joints become normal in a few days. _Alimentary Tract Symptoms._—The tongue may have a slight furring but the edges and tip are quite clean and red. Although anorexia exists with the fever the appetite tends to return with apyrexia. Constipation is usual. There is frequently tenderness of the epigastric region. _Genito-urinary System._—Other than for albuminuria and the presence at intervals of the causative bacteria in the urine, there is nothing of note, except the occurrence of orchitis in about 3 per cent. of cases. _The Blood._—The white count is about normal or slightly reduced—6500 on the average. The cells of lymphocyte type tend to show an increase in percentage with a corresponding reduction of polymorphonuclears. There is a secondary anaemia. The spleen shows early enlargement and tenderness. DIAGNOSIS =Clinical Diagnosis.=—The diseases most apt to be confused with Malta fever are typhoid fever, malignant tertian malaria, liver abscess, influenza, phthisis and kala-azar. Besides the agglutination, complement fixation or blood culture aids, we rely upon the sudden onset of joint involvement or neuralgic manifestations as indicating Malta fever. Usually the splenic enlargement about corresponds with that of typhoid fever but at times it may be so marked as to equal that of malaria or even kala-azar. The presence of rose spots as well as the marked apathetic state and the tendency to diarrhoea should aid in differentiating typhoid. Unfortunately for diagnosis the leucopenia and polynuclear percentage reduction is similar in the two diseases. In kala-azar the double temperature rise in 24 hours with the _Leishmania_ bodies in spleen puncture material, instead of _M. melitensis_, are differentiating. The short course and more sudden onset of influenza and the more marked pulmonary symptoms of phthisis should prove diagnostic aids. Liver abscess and empyema with their tendency to anaemia and sweating may prove confusing, but the history, leucocytosis and location of pain should differentiate. Then too the joint and nerve manifestations of Malta fever are absent.