In the bat Eptesicus fuscus the temperature of brown fat exceeded that of other tissues by about 3 degrees C during the late stages of arousal from hibernation. Heat production seems to be a major function of brown fat in the hibernating mammal.

A case of malignant thymoma with extrathoracic metastases is described and discussed. A review of the literature revealed only 11 such cases previously reported. Pertinent clinical and pathologic data are reviewed and discussed. The age range was 32 to 74 years, with a mean of 49.5 years. The duration of life from onset of symptoms to time of death ranged from 2 1/2 months to 14 years, with a mean of 3.9 years. The relatively rapid evolution from onset of symptoms to time of death was probably related to late diagnosis rather than to aggressiveness of the neoplasm, since this type of tumor is usually slow growing. At postmortem examination, all cases showed a large mediastinal tumor in addition to extrathoracic metastases. Microscopic examination of the tumors found 8 to be predominently epithelial, one made up of spindle cells, 2 of a combination of epithelial and spindle cells, and one of lymphocytic type. The rare occurrence of extrathoracic spread of thymoma is attributed to relative lack of host defenses, though in our reported case a strong desmoplastic reaction is held accountable for the longest reported survival (14 years).

Sites occupied by multilocular brown fat in the adult hamster are occupied by unilocular cells in very young animals. Immature brown fat cells are laid down in the unilocular cell matrix at 3 to 5 days of age. White fat in the hamster does not develop from cells closely resembling mature brown fat.

A case of multiple myeloma with hypogammaglobulinemia and absence of detectable light chain fragments in serum or urine was studied. Electron microscopy of myeloma cells in marrow revealed hypertrophied endoplasmic reticulum consistent with increased protein formation. Enzymatic dysfunction may have operated to inhibit completion of this process. Chromosome abnormalities in myeloma cells and peripheral leukocyte culture were consistent with neoplasia.

This investigation was concerned with analysis of the composition and metabolism of developing adipose tissues in the postnatal hamster. Particular attentions were given to the development of brown fat and the relationship of brown and white fats to each other. Correlations with previous histological studies are stressed. The parameters studied were water content, total lipid content, glycogen content, fatty acid compositions of total lipid extracts, malic dehydrogenase activity as assayed from oxaloacetate to malate, glucose‐6‐phosphate dehydrogenase activity and aldolase activity.