SPORE-DISCHARGE IN THE CLAVARIEAE 187 



vertically situated. Doubtless, owing to the vertical position of 

 the hymenium, the narrowness of the cylinders which the hymenium 

 covers, and the solitariness of the fruit-bodies, the wind is given 

 ample opportunity to carry away the discharged spores. 



In Pterula, the fruit-bodies are mostly branched. The branches 

 are filiform arid in some species, e.g. Pterula subulata, fuse where 

 they touch. Here, as elsewhere, union is strength and the fusion 

 of the component parts of the fruit-body to some extent compen- 

 sates for their individual weakness. The hymenium is said to 

 cover the surfaces of the branches, but as yet I have not had an 

 opportunity to verify this statement. Pterula, in having filiform 

 branches, has reached the extreme limit of the Clayaria type of 

 organisation. Owing to the fineness of its branches, it provides 

 far more surface area per unit of fruit-body mass for the develop- 

 ment of the hymenium than any of the other genera of Clavarieae. 

 As if to compensate for the fineness of the branches, the flesh of the 

 Pterulae is stiff and cartilaginous. It may be that species of Pterula 

 retain their vitality when dried and revive in wet weather, in this 

 way differing from the soft-fleshed species of Clavaria ; but of this, 

 up to the present, experimental evidence is lacking. 



According to Patouillard, 1 the genus Pterula contains about 

 twenty species, some of which have their branches slightly com- 

 pressed and the hymenium unilateral. Doubtless, the hymenium, 

 when unilateral, is on the under side of the flattened branches' 

 and not on the upper side. These species of Pterula with slightly 

 flattened branches are of especial interest from the point of view of 

 evolution. In Pterula the branches in most species are so fine that 

 they have some difficulty in supporting themselves in a strictly 

 vertical position and are therefore more or less inclined, with the 

 result that part of the hymenium looks more or less upwards. 

 As a reaction against this inconvenience, which has arisen from 

 pushing the Clavaria type of organisation to its extreme limit, 

 some of the species have become thelephoraceous, i.e. have developed 

 branches which are slightly flattened and dorsiventral with the 

 hymenium restricted to the under surface only. 



1 N. Patouillard, Essai taxonomique sur les Families et les Genres des 

 Hymenomycetes, Lons-le-Saunier, 1900, p. 42. 



