886 AN INVERTED HYMENIUM IN AGARICUS CAMPESTRIS, 



Moreover, this sporogenous tissue is completely covered by a thin 

 membrane, so that there can be no question of its having attained 

 its position through invagination. 



The examination of these abnormal mushrooms, therefore, 

 leads to the conclusion, that they represent a partial reversion to 

 an ancestral character. One would hardly expect a complete 

 reversion; and that it is only partial, is demonstrated by the 

 manner in which the spores are borne. 



The discharge and disposal of the spores in the Agaricaceje, 

 according to Buller(4), are brought about, as follows : — 



The special conidiophore, or basidium, usually bears four 

 spores, which are discharged successively, and each spore becomes 

 violently detached. The violent discharge of the spores prevents 

 the adhesive spores from massing together, and from sticking 

 fast to the gill-surface. At first, the spore is shot out horizon- 

 tally; then, under the influence of gravity, it describes a sharp 

 curve, and then falls vertically. The path described by the 

 falling spore has been appropriately called a sporabola. After 

 falling, under the influence of gravity, in the still air between 

 the gill lamellae till they reach the exterior, the spores are borne 

 away by the breeze. Basidia, being four sterigmata with four 

 spores attached, were found in my specimens in the inverted 

 hymenium; and it is obvious that, if the spores were discharged 

 in the normal way from the sterigmata and then started to fall 

 under the action of gravity, they would not get free from the 

 hymenium at all, but would fill up the spaces between the gills 



We have, therefore, a reversion to an ancestral condition so 

 far as the macroscopic characters are concerned, with a retention 

 of the modern condition so far as the microscopic characters are 

 involved. 



LITERATURE CITED. 



1. WoRSDELL, W. C. - Principles of Plant Teratology, Vol. i., p,33 (191o). 



2. Aquatias, p. — Intensive cultui'e of Vegetables on the French Sj'steni, 



p.153 (1913). 



3. WoRSDELL, W. C— Principles of Plant Teratology, Vol. i., p.3U(191o). 



4. BuLLER — Researches in Fungi, p. 144 (1909). 



