1. Studies were made on the crown-gall of Bryophyllum spp. and Helianthus sp. from the viewpoint of malignancy of the disease. 2. Comparing the effects of diseases in the life of annual and perennial plants with those of animals, it was concluded that the crown-gall of plants is a fatal disease with exceptions. 3. Characteristics of the tumors produced by the crown-gall disease on Bryophyllum spp. And Helianthus sp. were studied under the topics of (1), autonomous multiplication of tumor cells; (2), infiltration of tumor tissues within healthy tissues; (3), translocation of tumor tissues; (4), culture of tumor tissues; (5), grafting of tumor tissues on healthy tissues; (6), anatomy of the tumor strands; and (7), injury and alteration of healthy tissues produced by adjacent tumor tissues. 4. Most of the auther's original studies on crown-gall disease are contained in the above topic (7), and cover polyploid cell layers, cancerous cell layers, degenerated cell layers, and defensive cell layers in relation to tumor strands. Subjects are substantiated by semidiagramatic figures and plates.