Abstract
A black female mouse purchased from a breeder in New York City and belonging to a set of from 200 to 300 mice under observation by Mr. Horton of Columbia, in experiments on Mendelian inheritance, developed a tumor on the right fore leg. The shoulder and axilla were involved and the mouse could not use the leg in walking. At one point the hair had been scratched off and the skin bared but the tumor was not ulcerated. On removing, there was no evidence of hemorrhage and a solid tumor about the size of a hickory nut and weighing about 4 grams was taken out. It had become attached to the skin but was apparently not attached elsewhere. A piece of the tumor weighing about 1 1/2 gram was ground up with normal salt solution (3 c.c. normal salt to 1 gram of tumor material) and this was injected under the skin of the neck in twelve white mice. The remainder was fixed in 10 per cent. formalin and in Zenker's fluid. No tumor has yet appeared in the inoculated mice.
Dr. Ewing described the tumor from sections as an adenoma with glandular characters of the thyroid. Necrotic areas are few in number and very small; mitotic figures are rare.
Sections of the tumor put through the Levaditi silver nitrate method reveal the presence of Spirochæta micogyrata. The spirochzte is not widely distributed but may be found at various points in the tumor mass, especially in the few small vacuolar areas. It has the characters of the species described by Lowenthal in 1905 in a case of human ulcerated carcinoma. It varies in length from three to eight microns and has from four to thirteen turns or “nodes,” the average length of a node being six tenths of a micron.
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