ADJUSTMENTS OF FRUIT-BODIES 71 



in 45 minutes. After further practice in handling the material and 

 in making observations, I found a fruit-body which curved upwards 

 through a right angle in 17-."> minutes. It gave a distinct macro- 

 scopic reaction to the stimulus of gravity after 3 minutes' stimulation, 

 turned through an angle of 1 0° in the first 5 minutes, and through a 

 further angle of 80° in the next 12-") minutes. The pileus, therefore, 

 was turned through almost a complete right angle with an angular 

 velocity greater than that of the minute hand of a clock. This 

 angular velocity is far greater than that known for any Phanerogam 

 or, indeed, any other plant when stimulated by gravity. For a stem 

 to turn upwards through a right angle several hours are usually 

 required, whereas, as we have seen, the stipe of Coprinus plicatiloides 

 can perform this movement in 17-5 minutes. The latent period for 

 roots — the time required for the commencement of curvature after 

 continuous geotropic stimulation — is, according to Moisescu, 1 who 

 experimented on Lwpinus albus, Cucurbita, &c, at least 15 minutes 

 when one observes with the naked eye. On the other hand, the 

 stipe of the Coprinus made a distinct curvature in 3 minutes. The 

 remarkable rapidity of the geotropic reaction in the fungus is com- 

 parable with the reactions of tendrils to the stimulus of touch. 2 



Moisescu 3 states that with the microscope he could detect a 

 slight downward curvature of certain roots after one minute of 

 stimulation. In an experiment in which a fruit-body was tilted to an 

 angle of 45° and the stipe supported on a rest so as to prevent its 

 initial sagging from the weight of the pileus, a distinct upward 

 curvature was observed with a horizontal microscope of low magnifi- 

 cation in one and a half minutes. Probably further experiments 



1 Moisescu, " Kleine Mitteilung iiber die Anwendung des horizontalen Micro- 

 skopes zur Bestimmung der Reaktionszeit," Ber. d. deutschen hot. Gesell., Bd. XXIII., 

 1905, p. 366. 



2 The movements of very sensitive tendrils in certain species are even more 

 rapid than that observed for the stipe. Thus, after rubbing the inner side of a 

 tendril of a Cucumber and placing the rubbed surface in contact with a stick, I 

 observed that the tendril made a half-turn round its support in five minutes, a 

 whole turn in ten minutes, and one and a half turns in twenty minutes. The 

 temperature was 85° F. The mean angular velocity of the tendril for the first 

 ten minutes was 36 times greater than that of the stipe, although after twenty 

 minutes it had become only 5-3 times greater. 



3 Moisescu, loc. cit. 



