PANAEOLUS CAMPANULATUS 



249 



Figure by the arrows which mark the trajectories of a number of 

 spores which have been shot away from the hymenium in various 

 parts of the gills almost simultaneously. ,+*'" llm* z-omm. jUn. 



The spores in Panaeolus campanu- 

 latus are shot from their basidia 

 straight forward for a distance of about 

 O'l mm. (Fig. 85). The basidia in the 

 hymenium on the sides of the gills have 

 the axes of their bodies and of their 

 sterigmata almost horizontally situated, 

 and they therefore project their spores 

 in a more or less horizontal direction 

 straight outwards from the gills into the 

 interlamellar spaces. In still air, as I 

 have shown in Volume I, the projection- 

 velocity of any discharged spore is 

 almost instantly reduced to zero, so 

 that a spore, after travelling horizontally 

 a distance of about O'l mm., turns 

 sharply downwards through a right 

 angle and then falls vertically toward 

 the earth. I have called the peculiar 

 trajectory described by a spore a 

 sporabola. 1 The steady terminal rate 

 of fall of the spores of Panaeolus cam- 

 panulatus in still air is from 2 to 3 mm. 

 per second. 2 



The interlamellar spaces, although 

 less than one millimetre wide between 

 any two adjacent gills (as may be seen 

 by reference to the scale in Fig. 85), are 

 sufficient to permit of the escape of all the spores when the fruit- 

 body is oriented in a normal manner, i.e. when the end of the 



1 Vol. i, 1909, Chap. XVII, p. 185. 



2 For Panaeolus campanulatus, the exact horizontal distance of spore-discharge 

 and the exact rate of fall in still air have not been measured. The estimates given 

 above are based on measurements made for a considerable number of other species 

 having spores of various sizes. Cf. vol. i, pp. 142 and 175. 



FIG. 85. Panaeolus campanu- 

 latus. A vertical section 

 through the pileus-flesh and 

 several gills showing shape 

 and direction of gills. The 

 trajectories of a number 

 of spores in still air are 

 indicated by the arrows. 

 Magnification, 20. 



