Another species of tumour seems to be composed almost entirely of fatty matter insinuated amongst extended and delicate cellular substance, and has been therefore termed adipose. It is surrounded by a cyst of dense cellular tissue, and to this it loosely adheres; its bloodvessels are few, and it is of an inactive and innocuous character. It is generally lobulated, and often attains a large size. It is not only irregularly prominent on its outer surface, but in its whole circumference, and its lobuli often insinuate themselves to a great depth amongst nerves, bloodvessels, and other important parts; owing to this circumstance they frequently prove a source of the greatest inconvenience from their bulk, for of themselves they are neither hurtful, nor possess any disposition to involve those parts with which they are in contact. This tumour is found only in the cellular and adipose tissues. From its loose connection with its envelope, it admits of ready removal by operation. A tumour of this kind is here represented, which, but for this circumstance, owing to its awkward situation under the tongue, could not by any possibility have been extirpated. It is fully larger than an orange, and had caused very great suffering. It is not so much lobulated as fatty tumours generally are. The adhesions of adipose tumours are, however, rendered firm and more numerous by pressure or external stimulants—in fact, by whatever induces inflammatory action in its substance or in its surrounding connections; and from this cause the extraction is often rendered exceedingly difficult. The skin becomes thickened and of a red hue, and the tumour itself is much more vascular. From this cause it is apt to assume a new mode of action, and to change in structure and in character, invariably for the worse. I have removed a few tumours, originally of this benign species, but which had apparently degenerated and assumed a malignant action. In one, distinct indurated bands radiating from a central mass of the same kind, are discernible. In two others, as a consequence of pressure, condensation and ultimate softening had occurred. The largest alluded to was removed from betwixt the shoulders of a soldier, and had borne the pressure of his knapsack for eight or ten years. It was attached by a thickish neck, presented the common lobulated appearance of adipose sarcoma; but its external surface, its feel, and section, were very different.