2QO 



RESEARCHES ON FUNGI 



space. Each spore is projected more or less horizontally from 

 its sterigma with a considerable velocity ; but this horizontal 

 velocity, in a small fraction of one second, is reduced to 

 zero owing to the resistance offered to the passage of the spore 

 by the air. 1 Each spore, after having been shot more or less 

 horizontally to a maximum distance of 0-1-0-12 mm., makes a 

 sharp turn through a right angle and then, if the air is still, falls 



FIG. 97. Panaeolus campanulatus. A vertical section taken transversely to 

 the long axis of a gill showing the probable trajectories of spores discharged 

 from the hymenium (a portion of the area B in Fig. 96, p. 287). The 

 uppermost basidium has just discharged one of its spores which is being 

 projected horizontally and is carrying a drop of water with it. From the 

 hilum of another spore on the same basidium a water-drop has been excreted 

 to about maximum size : this spore is just about to be discharged. Three 

 trajectories of spores, discharged in still air, are indicated by the arrows ; 

 their horizontal portions have been represented as being (from above down- 

 wards) 0'12 mm., O'l mm., and O'll mm. in length. Magnification, 465. 



vertically downwards toward the earth (Fig. 97). The steady 

 terminal velocity of fall for a spore of Panaeolus campanulatus is 

 about 2-3 mm. per second. 2 



In Panaeolus campanulatus, just as in all other Hymeno- 

 mycetes, the drop excreted at the spore-hilum just before spore- 

 discharge is carried with the spore during its flight through the 

 air. 3 This is represented in Fig. 97 for the spore which has just 

 left the uppermost present-generation basidium. 



We have seen that all the elements represented in the 



1 Vol. i, 1909, p. 185. 2 Cf. p. 249, foot-note. 



Chap. I, pp. 14-16. 



