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New vo^^ 



Studies on a Disease of Pueraria caused 

 by SyncPiytrium Puerariae. 



(Resume) 



By 



S. Kusaiio. 



With Plate I. 



Synchytrium Puerariae Miyabe, which has hitherto been in- 

 cluded, apparently with good reason, in the group of Uredineae,'^ 

 produces on Pueraria Thunbergiana gall-like swellings of various 

 sizes upon the leaves and stems (Figs. 1-3, 7-9). Unlike the 

 other members of this genus it is characterized by having no 

 resting spores, and by infecting, not the epidermal, but the other 

 internal cells which have very little or no chlorophyll. Besides the 

 cytology of the host cell and the fungus body itself, the writer 

 devotes the present paper to the studies on the physiology 

 and biology of the fungus. While the swarm-spores infecting the 

 leaves develop mature sporangia after about four weeks, those on 

 the stem are exceedingly delayed in development and develop 

 sporangia in the spring of the next year. .For the rupture of the 

 sporangium-sorus lying deep under the epidermis it necessarily 

 requires a strong osmotic pressure of the surrounding host 

 cells, which corresponds to 3^2 atomospheres {l^/o potassium 

 cn nitrate) (Figs. 4, 5). In water the mature sporangium can 

 produce swarm-spores after 1.5-2 hours. Meanwhile it swells 



I 



CD up absorbing much water, and thus, exerting a strong internal 

 ^ pressure, its wall bulges out and then ruptures at one or two 

 :iE thinner portions (Figs. 15, 16). The plasmolysis experiment 



1) Aecidium Puerariae P. Henn., Monsiiuia I. 1900. p. 4; Uromyces Puerariae 

 Diet., Engl. bot. Jahrb. XXVIII. 1901. p. 282. 



