Octimsj K. MIYABE.— ON CHRYSOMYXA EXPANSA. 261 



and .22-. 15 mm in width. The average of twenty measurements 

 is .41 x .33 mm. 



The number of the sori in a given macula is quite consider- 

 able. A fair idea may be formed from the following enumera- 

 tions. In a spot 9x7 mm, 110 sori were counted ; in 4x4 mm 

 spots, 58, 65 and 68 sori; in 4x3 mm, 36 and 53 ; in 3 x 3 mm. 

 42 ; in 2 x 2 mm, 22 ; and in 1 x 1 mm, 13. 



The teleutospores are cylindrico-prismatie, and in their lat- 

 eral view are oblong, elliptical or ovate, measuring 11—25 /'. in 

 length and 8-13 [i in width. They are arranged in very long 

 chains with the length of about .35 mm at the middle of the 

 sorus, where the chain is composed of about 11 to 18 cells. 

 From the nature of the cell contents, the upper 8 or 10 cells 

 should be considered as the teleutospores, and the rest as the 

 sterile stalk cells. The stalk cells have narrower diameters 

 (7—8 fi) and lighter colored or hyaline contents. Sporidia are 

 elliptico- or oblong-reniform, 4-6// in length and 2.5-1// in 

 width. 



In 1879, de Bary (1) by his painstaking researches proved 

 that Chrysomyxa Rhododendri is a heteroecious species and 

 forms its Aecidium stage on the leaves of Picea excelsa. It 

 would be quite natural for any one to regard our species as 

 being also heteroecious and look for the host of its Aecidium 

 stage among the species of our spruce. In 1908, Mr. Otosaku 

 Saito kindly sent us a specimen of Peridermium on the leaves 

 of Picea Gkhni (12), which had been collected by him in the 

 Kusunai National Forest not far from Ochiai. When the author 

 examined the specimen, the idea at once arose in his mind, that 

 this Peridermium might be a stage of Chrysomyxa on Rhodo- 

 dendron brachycarpum, which Mr. Hiratsuka had collected at 

 about the same place in the previous year. So the author went 

 to Ochiai and Kusunai in the October of the same year to ob- 

 tain for the infection experiments the seedlings of R. brachvear- 

 pum, whose leaves had already been affected. By that time, 

 the affected leaves of the spruce had already dropped off. 



Some of the seedlings survived the winter and produced the 

 teleutospore sori in the following spring, when the infection 



