26 



the province of Hidachi and those sent by Professor S. Tanaka of our 

 College which he had received from his friend in Urawa, in the 

 province of Mnsashi ; and partly from the alcoholic specimens collected 

 myself at Koraatsu, in the province of Iyo, in the summer of 1896, 

 during a botanical excursion to Sikoku. Before my excursion to 

 Sikoku, I saw for the first time a diseased plant bearing an immense 

 number of oospores at Kantarimura, Otokuni County, in the province 

 of Yamashiro, in the latter part of august, 1894, but at that time, 

 the seaBon was too late to find out its conidial fructification. 



A plant of Setaria italica attacked by this fungus shows the 

 peculiarity of bearing oospores and conidia of the parasite separately 

 on different leaves and organs. 



In fact the oospores are formed either in the metamorphosed floral 

 leaves of the deformed ears (Fig. 2), or in the etiolated leaves on the 

 upper part of the stem, of which the uppermost are usually rolled 

 and remain unexpanded (Fig. 6), while the conidial fructifications are 

 always borne on the under surface of the green leaves on the lower 

 part of the stem. The leaves in which the oospores are formed are 

 twice as thick as the healthy leaves, the latter measuring from 

 320 p to 168 n in thickness. On the other hand the cell wall of 

 the mesophyll of the diseased leaf is less thickened and less silicious 

 than that of the ordinary leaves, thus imparting to the leaf a peculiar 

 character of splitting into shreads (Fig. 6). 



Both the foliage and floral leaves which contain oospores appear at 

 first white, then turn to yellow, light brown and finally to deep brown 

 as the spores ripen, or in the case of floral leaves the color becmoes 

 somewhat purple. The glumes and pales, composing the abortive flower, 

 overlap one another so as to form a somewhat curved cylindrical body 

 and assume an external appearance somewhat like the ergot of rye 

 (Figs. 1, 2, 3 and 5). 



The mycelium which is intercellular, is furnished with small 

 wart-like haustoria and developes sets of sexual organs in the inter- 

 cellular spaces in the deeper part of the mesopbyll-parenchyma as 

 well as in the air-cavities under the stomata (Fig. 7). 



The fertilization is effected not by means of a fertilizing tube 

 but by simple contact, when it is probable the male element of the 

 antheridium passes into the interior of the oogonium (Fig. 8). The 

 fertilized oosphere surrounds itself with a thick coating, which when 



