On the Genetic Connection between 



Coleosporium on Aster scaber and 



Peridermium Pini-densiflorae P. Henn 



By 

 Y. Orishimo, NogakushL 



Pinus densiflora and Thunbergii are the two commonest 

 pines growing in Japan. On the leaves of these pines, we find 

 two species of rust fungi, respectively called Peridermium Pini- 

 densiflorae P. Henn. and Perid. Pini-Thunhergii Diet. From the 

 beginning of May, these fungi appear abundantly on the leaves 

 of the pines in the botanic garden and arboretum of the Agri- 

 cultural College of the Imperial University of Tokyo. Later in 

 the season, there appaer on different host plants several species 

 of Coleosporium. In Europe the relations of different species of 

 Coleosporium to those of Peridermium have been investigated 

 by different observers and the genetic connections between ma^ 

 jority of their species have been experimentally proved. 



But in Japan no such investigations have ever been done 

 except a single case of Peridermium gigatneum Mayr.* Professor 

 Shirai suggested me to take up the subject, and under his 

 direction I have made several infection experiments during the 

 academic year 1907—1908 in the botanical laboratory and gar- 

 den of the Agricultural College of the Imperial University of 

 Tokyo. In these experiments, I have obtained some positive 

 results of which I want to niake some notes in the following 

 lines. 



Experiment I. 



(Trial experiment.) 



More than twenty species of Coleosporium are known as 

 occurring in Japan on different host plants, which can be seen in 

 the following table. 



* M. Shirai, On the genetic Connection between Peridermium giganteum (Myr.) 

 Tubeuf, and Cronartium quercuum (Cooke) Miyabe. Bot. Mag. Tokyo. 1899. Vol. 

 XIII. P. 74-79. 



