2 THE BOTANTCAL MAGAZINE. [y^i, xxii. No. 252, 



shows that the sporangium contains when in this state a 

 certain substance approximately isotonic with S% potassium 

 nitrate. 



For the germination of the sporangium drops of dew on the 

 host was found to be the most favourable fluid among those 

 on several other plants, rain-water, tap-water, and distilled 

 water. Insufficient supply of oxygen or exposure to too high 

 temperature {ca. 30°C.) delays the germination. 



The optimal temperature for the active movement of the 

 swarm-spores is 20— 21°C., at which the velocity is approxi- 

 mately 0'05 mm. per sec. in average. The motion takes place 

 only between 30-31°C. and 4-5°C. 



The tactic movement of the swarm-spores is typically 

 phobotactic. They are responsive to aerotactic, thermotactic, 

 and chemotactic, but not to thigmotactic and phototactic 

 stimuli. In the chemotactic experiment the host tissue or its 

 extract was tested, and the positive chemotaxis was induced 

 most remarkably by a trichome or its extract and less mark- 

 edly by hyaline parenchyma, while green tissue or extract of 

 young shoots induced a strong negative chemotaxis. The 

 writer found in the last mentioned tissue or extract a large 

 amount of tannin which he considered to be one of the com- 

 ponents exercising the repellent action upon the spores. 



The noteworthy facts obtained in the cytological studies 

 are : — in the fungus body, the formation of numerous secondary 

 nucleoli, the derivation of chromatin from both secondary and 

 primary nucleoli, the bodily transformation of the daughter 

 chromosomes into the nucleolus of the daughter nucleus, and the 

 appearance of a centrosome-like body at the end of the nuclear 

 division which is concerned in the formation of the nuclear mem- 

 brane, and, in the host, the formation of symplast. These facts 

 were partly reported already in this Magazine^^ and the " Cen- 

 tralblatt fiir Bakteriologie etc.""^ 

 Botanical Institute, 



Agricultural College, Tokyo. December, 1907. 



1) Vol. XXI. 1907. p. 118 and (149). 



2) Bd. XIX. 1907. p. 538. 



