tinguish them, while others are three or four times larger than the normal tubule of the kidney. In addition to these lumina of the gland tubules there are also large alveolar spaces which are very irregular in outline. Desquamated epithelial cells undergoing degeneration are found in the lumina of many of the larger tubules.

The epithelial cells lining the tubules are quite embryonal in character and are arranged in a single layer. These cells usually contain a moderate amount of protoplasm; the nucleus is round and possesses a medium amount of finely granular chromatin. The epithelial cells lining the smaller tubules are round, somewhat larger than those lining the larger tubules; their nuclei do not contain quite

FIG. 39.-Embryonal adenosarcoma of swine, showing osseous tissue. X 100.

so much chromatin. The epithelial cells forming nests in the connective tissue are also round; the nuclei are vesicular and contain about the same amount of chromatin as those lining the small tubule.

If one compares the tumor cells as such and their arrangement where they form the tubular structures (see fig. 35) with the cells and the arrangement of the latter in the tubules of the Wolffian body in pig embryos 9 to 12 mm. long (see fig. 36), a striking similarity may be easily noticed.

The connective tissue is largely composed of fusiform cells with rod-shaped nuclei. These cells have very much the character of involuntary muscle cells. (See fig. 37.) The, connective tissue just

described is distributed unevenly throughout the tumors. In some places there are hemorrhagic areas in the connective tissue.

Two of the tumors contained cartilage which was distributed here and there throughout the growth. (See fig. 38.) In one of the two a small amount of cartilage was found in the capsule.

One of the tumors contained a large amount of osseous tissue; this tissue was well developed and occupied a place near the center of the tumor. (See fig. 39.) A careful examination for striated muscle fibers was made of many sections from the eight tumors submitted, but none were found. In these respects only were these new growths different from those found in children.

55284-08-17

DERMAL MYCOSIS ASSOCIATED WITH SARCOPTIC MANGE IN

HORSES."

By A. D. MELVIN, D. V. S.,

Chief of the Bureau of Animal Industry,

AND

JOHN R. MOHLER, A. M., V. M. D.,

Chief of the Pathological Division.

INTRODUCTION.

While supervising the field work of the Bureau of Animal Industry in 1901 the attention of the senior writer of this paper was attracted to a peculiar skin disease among the horses on the Umatilla Indian Reservation, near Pendleton, Oreg. A preliminary examination of the scurf and hide of a number of infected horses indicated that the disease was somewhat dissimilar to any disease produced by animal parasites and suggested the possibility of the cause being of vegetable origin. This conclusion was reached owing to the generalized appearance of the lesions on the affected animals, the apparent short period of incubation, and the inability to find any mange parasites, even though many animals were inspected and the scabs scraped deeply, warmed, and examined by a good hand lens. That the disease was contagious was evident from the history of the outbreak and from the great number of animals found to be suffering with the affection in various stages of development. At that time about 6,000 horses were kept on the reservation, and it was estimated that over 2,500 of these animals were more or less affected with this cutaneous disease.

Owing to the interest attached to the determination of the true. character, as well as with the hope of elucidating the causation of the disease and of suggesting appropriate treatment, portions of the hide from several badly affected animals were obtained and forwarded to the pathological laboratory at Washington for investigation.

PRELIMINARY INVESTIGATION.

An examination of the first samples of skin forwarded to Washington failed to show any animal parasites or any indication of their presence, such as the egg cases or eggs of a parasite or its gallery or

• This paper was presented at the annual convention of the American Veterinary Medical Association, Kansas City, Mo., September 10-13, 1907.

burrow. Both stained and unstained scrapings from the skin were examined at first and then sections of the tissue were prepared and studied. In each instance a large number of sickle-shaped spores of a fungus were observed, principally in the hair sacs, though occasionally in the sebaceous glands. Other specimens of skin were received from time to time, until about 30 samples in all had been forwarded. In all these specimens this identical fungus was found invariably, and in addition some of the hides showed the presence of the mange parasite Sarcoptes scabei var. equi, but they were not in sufficient numbers on any sample to account for all the lesions observed. In the majority of cases, however, only the fungus was present to account for the skin alterations, and an attempt to isolate this organism was thereupon made.

The hide was seared with a hot spatula and small cubes were removed with sterile forceps, smeared on potato medium, and then placed in a test tube containing bouillon. Potato and bouillon media were also inoculated direct from the seared surface of the skin by means of the platinum needle. Several of the remaining hairs on the hide were also used for making cultures by pulling them out with sterile forceps, snipping off the root end by means of sterile scissors and allowing them to fall into a tube containing potato or into melted agar, which was afterwards plated. The first successful culture was obtained on potato as a result of this last method of sowing the root of the hair upon this medium. Cover-glass preparations made from these various cultures showed the presence of a fungus containing numerous crescentic, sharp-pointed, segmented spores similar to those found in the microscopic sections of the skin and which were recognized as belonging to the group of fungi known as Fusarium. To this species of the fungus Nörgaard has proposed the name Fusarium equinum, since up to that time no other species had been known to exist parasitically in or on horses.

a

In 1904 Sheldon described the presence of a dry rot on corn caused by a fusarium called by him Fusarium monoliforme. This fungus was found by Peters to be present on all the farms where a peculiar disease of animals was investigated. The horses would lose their hair and hoofs and were said by the stockmen in the community to be" alkalied." Cattle and hogs on these farms were likewise said to lose their hair and the chickens to lose their feathers, and Peters attributed it to the feeding upon moldy corn affected with Fusarium monoliforme. Feeding experiments conducted upon hogs with this corn, as well as with pure cultures obtained from the moldy corn, reproduced the symptoms in the experiment animals.

a Science, December 6, 1901, p. 898.

Seventeenth Annual Report, Nebraska Agricultural Experiment Station, p. 23. c Ibid., p. 13.