Hyperplasia and atrophy of marrow in the lower mammals follow much the same conditions as in higher groups. During acute general infections, as by the paracolon bacillus in carnivores, it is common to find a distinct increase in the mononuclear centres, while in suppurative lesions a polynucleosis results. The bird, however, responds less readily with leucocytes, judged by cross sections of blood vessels and the activity of the marrow. The latter may show a myeloid picture, but mononuclears without granules, with deeply staining nucleus and protoplasm, are usually more numerous; two cases recently studied, one of tuberculosis and one of pneumonia with general congestion, had similar bone marrow— pale homogeneous red with distinct mononucleosis, more outspoken, however, in the former case. Pigment is not common in the avian marrow. The relation of the marrow to general conditions has been mentioned in the foregoing pages, but perhaps the following diagnoses will illustrate other connections seen among our records: Bactrian Camel (_Camelus bactrianus_).—Hydatid disease of lung and liver. Hemorrhagic enteritis. Atrophic bone marrow. Calcified areas in thyroid. American Gray Wolf (_Canis mexicanus_).—Cretinoid. Hemorrhagic external pachymeningitis with craniotabes. Secondary hyperplasia of thyroid with colloid. Chronic lymphatic hyperplasia. Chronic interstitial nephritis. Chronic enteritis. Osteogenesis imperfecta. Hemorrhagic bone marrow. Concentric hypertrophy and dilatation of heart. MYELOMA. Perhaps no pathological condition has given rise to more varied opinions than the tumor-like hyperplasias of the bone marrow, growths resembling bone sarcoma with and without giant cells—myeloma, chloroma, pseudoleucemia ossium and many others. In brief only two cases occur in our series which could be admitted to this category. There have been osteomata, but they were so clearly local tumors that they cannot be included in myeloid neoplasms that are assumed to be systemic in nature. Here is not the place to engage in a discussion of the correct classification and nomenclature since there are included only the aleucemic newgrowths usually assumed to originate from blood-making cells. The first case seems to be a myeloma because of the involvement of many bones and the infiltrates in the liver. Judging by the cross section of blood vessels there is no leucemia, but of course this is not final, although somewhat supported by the normal size of the spleen and lymph nodes; lymphatic structures need not be enlarged in myeloid leucemia although they usually are. Beechy’s Gopher (_Citellus grammurus beecheyi_). Adult ♂ . Gradual loss of power in limbs beginning about two weeks ago. No other symptoms. DIAGNOSIS.—Multiple myeloma. Anemia. Acute parenchymatous nephritis. Chronic ulcerative gastritis. External Appearance.—General condition fair, hair in good condition. Fully developed animal. Muscles contained no fat.