1. The optimum temperature for germination of uredospores of Uromyces Fabae, f. sp. Viciae-Fabae seems to range from 16° to 22.5°C. 2. On film of sterilized water at 20° to 22°C, the uredospores began to germinate within 50 minutes, and in 1 hour the two to four small knoblike germ tubes pushed out. After 1.5 hours, one of the germ tubes in each spore especially developed faster and more vigorously than the rest measuring 42μ long. Then the germ tubes reached 112μ in length within 3 hours, 151μ within 4 hours and 272μ within 5 hours. After 12 hours, they attained a length up to 560μ and branched. 3. In the germination of the uredospores, the germination percentage and the development of the germ tubes were approximately the same whether in light or in darkness. 4. The uredospores showed good germination in various concentrations of five kinds of carbohydrates: maltose, lactose, d-glucose, sucrose and l-fructose. 5. The uredospores lost vitality by the wet heat treatment at 46°C for 5 minutes exposure, at 42° to 44°C for 10 minutes, at 40°C for 20 minutes and at 38°C for 30 minutes. 6. The uredospores kept at 0° to 5°C did not lose their viability for more than 75 days. 7. The highest development of uredosori took place at 14° to 24°C, and infection gradually decreased toward the higher and the lower temperatures. 8. The fact that uredosori occur abundantly on the upper surface of broad bean leaves as well as on the lower, is due to the characters of the epidermis of the host, most important of which is the almost equal number of stomata per unit area of both surfaces. 9. The uredosori appeared sooner and in great abundance on the most vigorous plants. 10. All the varieties of broad bean and pea tested have appeared susceptible to Uromyces Fabae f. sp. Viciae-Fabae, although certain differences in susceptibility have been found among different varieties of pea.
The author has studied on the spodograms of the leaves of Shibataeachinensis NAKAI and found the following microscopical characters which make it possible to distinguish this species from Shib. Kumasaca NAKAI. 1. The number of cell rows constituting the band of articulation cells varies mostly 2-4 or more, according to the distance from the midrib. 2. Silica cells which are found in the epidermis on the upper surface of leaves are few in number. 3. On the under surface of leaves there are no ordinary hairs, but a few geniculate ones.