70 



RESEARCHES ON FUNGI 



to unilateral illumination, the stipe made a positive heliotropic 

 curvature, and oblique growth toward the source of light went on 

 all day (C and D). When darkness supervened, the stipe still con- 

 tinued to grow in the direction it had taken up during the previous 

 day. Toward morning on the next day, it gradually curved verti- 

 cally upwards, thereby indicating that it had become geotropically 

 sensitive. After the stipe had been growing away from the earth's 

 centre for about three hours, the pileus expanded in a horizontal 

 plane and discharged its spores (E). Spore-discharge lasted for 

 about an hour and a half. Soon after its completion the fruit-body 



Fig. 26. — Coprinus plicatiloidcs. Avoidance of an obstacle by successive reactions 

 to the directive stimuli of light and gravity. A, paper cap shown in B-E in 

 section. 13, young fruit-body covered with the paper cap on the afternoon of 

 the first day. C, the fruit-body at daybreak on the second day : the arrow 

 shows the direction of the chief incident rays of light. D, the fruit-body 

 at the end of the second day. E, the fruit-body about noon on the third 

 day. Natural size. 



collapsed. The successful avoidance of an obstacle and subsequent 

 uplifting of the pileus, as illustrated by the experiment just recorded, 

 affords excellent evidence of the biological importance of the re- 

 actions of the fruit-body to external stimuli. 



In order to test the sensitiveness of the stipe to the stimulus of 

 gravity, a vertical fruit- body, attached to its dung ball, was tilted 

 into a horizontal position. A distinct reaction was noticed in about 

 10 minutes, and the pileus was raised into the erect position again in 

 1 hour 15 minutes. By using specimens a little less developed, a 

 greater sensitiveness was observed : the plane of the base of the 

 pileus was turned from the vertical to the normal horizontal position 



