Note 4 — DISEASES OF THE SKIN.

Descazeaux has shown that the worms found in these summer sores are probably larval forms of the stomach worms of the horse, Habronema megastoma, H. microstoma, and H. muscæ. Ransom has shown that the larval stage of H. muscæ develops in the common housefly, the fly becoming infested as a maggot in horse manure. Infestation with the adult worms in the stomach of the horse (Pl. V, fig. 4) may take place through the ingestion of such infested flies, or by the escape of the larva from the proboscis of the fly as it feeds on the moist lips of the horse. In view of this it may be surmised that summer sores may arise as the result of flies so infested feeding on the moisture on the skin of the horse. In some forms of summer sores along the abdomen there are found immature stages of Habronema which apparently have just escaped from the egg and which are younger than some of the stages found in the fly. In this case it is surmised that these embryos from the manure enter the soiled skin of the horse, as it lies down on dirty bedding and manure, and develop in the skin as they would ordinarily in the fly. Descazeaux calls these summer sores cutaneous habronemiasis.

Preventive measures consist in the removal of the adult worms from the stomach of the horse by the use of anthelmintics, the destruction of the embryos in the manure, fly-control measures, and the use of clean bedding.—M. C. HALL.