IIiratsuka: Studiks on thi; Flax Rust 1 3 



The next sowing was made on May i8 on IJniitn tisitatissiinuin, giving rise 

 to sperniogonia on May 26, and aecidia on May 30. 



In Japan, for a number of years attempts liave been made to study a full 

 cycle of development of the fungus by Naoiiaku Hiratsuka, Kenji Miyaue 

 and other phytopathologists, but they failed to secure the germination of its 

 teleutospores. The writer also could not succeed in observing any germinating 

 teleutospore in the spring of 1923 and t924, but, in the spring of 1925, he at 

 last obtained successful results. Several bundles of flax straw affected by the 

 teleuto-stage of the rust fungus were obtained in the fall of 1924 and they were 

 kept under the snow over winter in the field. On April 14 of the spring of 1925, 

 the writer picked up several specimens of over-wintered teleutosori and kept 

 them in Petri-dishes in a moist condition for a week at room temperature. On 

 April 2 r , the u-riter made many longitudinal sections of the teleutosori samples. 

 They were then floated on redistilled water. Twenty-four hours after, they 

 showedstrong germination and many basidiospores were produced. Then, on 

 April 22, these basidiospores were inoculated on Larix Kaeinpferi Sarg., Abies 

 Mayriana Miyabe et Kudo and Linum usitatissivtuin L. (Saginaw). These three 

 host plants were tested in two series. The first series was kept in the green-house 

 after the inoculation and the other series was tested out of doors. On May 4, 

 spermogonia began to appear on the cotyledonous leaves and stems of the seed- 

 lings of Linum usitatissimwn L. in the latter series. However, in the first series 

 of Abies, Larix and Linum, no sign of spermogonia appeared. This failure is 

 probably due to the higher temperature in the green-house. Further, on May 

 19, the writer also found numerous spermogonia on the cotyledonous and ordina- 

 ry leaves and stems of the seedlings in the field plot. Then, after three or 

 four days, aecidia appeared. Over the soil of this plot, the rusted flax straw 

 had been spread and kept in place over winter. Six days after the appearance 

 of the aecidia, a large number of uredosori were produced on every portion of 

 the same host, and then, teleutosori appeared. 



