-( 48 )- 



in intercellular spaces. They are septated and branched, 2.4 3.4/i in width. They 

 send out through the stomata of the host plant and sometimes through the ruptured 

 epidermis, small tufts of conidiophores, commonly two or threo in number. They 

 are simple, but sometimes two of them may unite with each other at the base. 

 The length of the conidiophores ranges from 102 /M to 174//,, and the diameter at the 

 central portion varies from 3.4/u, to 6.8/jt, the basal portion being somewhat broader. 

 They are septated 2-4 times, light sooty-colored, while, their spore-baaring ends 

 are colorless and thin walled. The spores are formed on the tips of the 

 conidiophores. They vary a little both as to form and size. They are generally 

 oblong in shape, somewhat curved at the middle and septated from four to six 

 times. The end of the spore attached to the conidiophore is marked by a small 

 scar. The wall of the spore is smooth, generally very thin ; but we rarely 6nd the 

 spores with a thick wall, about one fourth of the shorter diameter and light brown 

 in color. The size of the spore varies from G9yu. to 82/z, in length and from 13.6/j 

 to YlfJ. in width. 



Infection and cultural experiments. On June 16th, the spores from the 

 diseased leaf were sown in drops of water on the under surface of each leaf of two 

 young rice plants, and the plants were kept under a bell jar. After four days the 

 symptoms of the disease appeared on the leaves with spots of the usual color and 

 shape, in whose tissue the fungus hyphae were detected. I did not succeed to 

 observe the growth of a conidiophore of the fungus. The spore germinates in well 

 water within two hours at the room temperature of 22C. The germ-tubes are 

 usually produced from both ends of the spore, and as the young hyphae grow in 

 length, the septa in the germinated spore are often dissolved away, the contents of 

 the middle cells being transfered into the young hyphae. The germ-tube from the 

 lower end of the spore grows straight, slightly avoiding the scar mark of the spore 

 already mentioned. Often the germ-tubes branch bilaterally, either directly from 

 the spore or after growing a few micrometers. As the hyphae grow in length a few 

 branches are formed, the contents at the basal portion being always carried 

 forward for the nourishment of the growing points. /W^lie spores sown in the 

 decoction of the host leaves germinate as in the above case, but the rate of the 

 growth of the young hyphae is very much more rapid. Two days after germination 

 the young hyphae are much more branched, often septated and filled with ref ringenfc 

 contents. After a week each portion of the septated hyphae become much thicker- 

 walled and brownish in color, becoming at length into a number of chlamydospores, 



