MICRO-ORGANISMS IN TUMORS.

The unsolved etiology of tumors is the subject of continued investigation in many different laboratories. In a recent article Podwyssotski¹ refers to the apparent hopelessness of demonstrating satisfactorily the parasitic nature of many cellular inclusions in human and animal tumors. He reports some experimental injections into various animals with pieces of parasitic, tumor-like growths upon cabbage and similar plants. The name of the parasite in question is plasmodiophora brassicæ Woron, and it belongs to the myxomycetes. The resulting growths in the animals experimented on were of mesodermal origin and resembled, in the progressive stage, large round-celled sarcomas; the growths developed especially in the perivascular spaces, and were formed largely by proliferation of the fixed cells. Spores of the parasite just mentioned were found united in smaller or larger plasmodial masses within the new cells; in many cases the cells were so distended that they ruptured and underwent disintegration. Giant