100 



RESEARCHES ON FUNGI 



looking position of the hymenium, the form of the basidium, the 

 mode of attachment of a spore to its sterigma, and some sporabohc 

 trajectories are shown in Volume I, Fig. 56 (p. 165). The spores 

 are large and globose and each one comes to contain one or 



more bulky oil-drops or guttae. The 

 presence of this oil helps to account 

 for the fact that the specific gravity 

 of the spores only just exceeds that 

 of water .1 It was the determination 

 of the radius, the density, and the 

 terminal rate of fall in still air of the 

 spores of Amanitoj^sis vaginata which 

 enabled me to make the first rough 

 test of the accuracy of Stokes' Law 

 for the fall of minute spheres in a 

 gaseous medium. ^ 



There is no essential difference 

 between the arrangement of the 

 spores in Amanitopsis vaginata 

 (Fig. 43, C and D) and in Amanita 

 rubescens. It is interesting to note 

 the resemblance of the structure of 

 the hymenium in species of two 

 genera which are generally regarded 

 as being closely related to one another. 

 Collybia radicata, C. velutipes, C. 

 dryophila, and C. fusipes. — All these 

 four fungi have the loose type of 

 hymenium characteristic of the Armil- 

 laria Sub-type. The accompanying illustration (Fig. 46) shows the 

 spore-picture for a piece of the hymenium of Collybia radicata when 

 seen in surface view. The scattered arrangement of the basidia 

 is very marked. There is evidently no massing of basidia of like 

 ages into compact groups, so that once more we have a striking 

 contrast with the appearance of the hymenium of Panaeolus cam- 

 panulatus. The fact that four species of Collybia all possess the 

 1 Researches on Fungi, vol. i, 1909, pp. 154-156. ^ j^d,^ pp. 164-173. 



Fig. 45. — Amanitopsis vaginata. 

 The fruit-body shown in Fig. 

 44 removed from the ground 

 and standing upon its pileus. 

 The volva surrounding the 

 base of the stipe is now well 

 displayed. Photographed by 

 J. E. Titley 

 size. 



About ^ natural 



