232 



MYCOLOGY 



the primary ones. The gills may be free from the stipe, adnexed, or 



even decurrent. 



A section of a mature gill shows the following disposition of the 

 hyphal layers. The central part of the gill consists of paraUel, down- 

 ward directed hyphae, that form the trama. Running out obliquely 

 from the trama are shorter ceUs which constitute the subhymenium. 

 The basidia, together with their accompanying paraphyses and cysti- 

 dia, form a paHsade-Uke layer (the hymenium) whose cells stand at 



right angles to the tramal hyphse. 

 The basidia are furnished with 

 sterigma, which beat the basidio- 

 spores (Fig. 92). In such forms 

 as the common mushroom, the 

 gill chamber is at first closed by 

 a veil known as the partial veil, 

 or velum parliale, which ruptures 

 when the pileus expands. The 

 part of this membrane attached 

 to the stipe becomes the annulus: 

 while the other part remains at- 

 tached in a shreddy condition 

 to the edge of the cap. The 

 species of A maniia have a univer- 

 sal veil which covers the whole 

 fruit body, and as this enlarges 

 the velum universale is torn trans- 

 versely, the lower part forming 

 the death cup, or volva, and the 

 upper part sometimes remaining 

 in the form of flaky pieces, which 

 are distributed irregularly over the upper surface of the cap (Fig. 93). 

 A frill-like annulus is also found at the top of the stipe in the Amani- 

 tas. It does not represent a portion of the partial veil in the Amanitas, 

 but is a membrane which is formed from a thick, loosely felted 

 layer, which separates as elongation proceeds from the surface of the 

 stipe, retaining its connection with the stipe where the stalk joins the 

 cap. It is pulled away from the stipe by retaining its connection with 

 the edges of the pendant gills as a continuous membrane, which covers 



Fig. 92. — Coprinus stercorarius with 

 young and mature sporophores with gills, 

 basidia and basidiospores and cystidia. 

 (Afler Brefeld.) 



