ATKINSON: LEPIOTA CRISTATA AND L. SEMINUDA 221 



crumbles and with light friction is easily removed down to the 

 surface of the pileus. But since no definite pileus surface layer is 

 organized as in certain species of Coprinus as in C. micaceiis, C. 

 radians, etc., the pileus does not become smooth by desquamation 

 as it does in those species. The distinction between blematogen 

 and pileus and stem is well shown in figures 23, 26-28, 32, and 33. 

 In FIGURES 26-28 it has cracked away from the pileus leaving the 

 surface of the latter rough from fragments of the blematogen or 

 "universal veil," which are still concrete with the pileus surface. 

 The partial veil. — The partial veil, as in Lepiota cristata, con- 

 sists of a short section of the blematogen, and of the ground 

 tissue between the margin of the pileus and the surface of the 

 stem. This ground tissue forms a thin zone in comparison with 

 the thick zone of the blematogen. In figure 37 it is about one- 

 third the thickness of the blematogen, but a large portion of the 

 latter has crumbled away. The proportion is better shown in 

 figure 23, where the ground tissue is about one-fourth to one-fifth 

 of the blematogen, but the limit between the two elements is not 

 definitely drawn. At and just below the apex of the stem the 

 thickness of the ground tissue of the partial veil is much greater. 



Primary differentiation of basidiocarp 

 In the species of Agaricaceae with endogenous origin of the 

 hymenophore, there appear thus far to have been described three 

 types of differentiation of pileus, stem, and hymenophore funda- 

 ments in the primordium of the young basidiocarp. 



1. The pileus area or primordium, is outlined first, as repre- 

 sented by Hypholoma suhlateritiitm and H. fascicular e (Miss Allen, 

 '06; Beer, '11), Amanita rubescens (deBary, '66, '84, '87), 

 Amanitopsis vaginata (Atkinson, '14). This type was observed 

 by Fayod ('89, p. 279). The pileus primordium he called the 

 " couche pileogene." He arrived at the conclusion that this type 

 prevailed in the Agaricaceae. 



2. The hymenophore primordium is outlined first. This type 

 is represented by Agaricus campestris (Atkinson, '06), Agaricus 

 arvensis (Atkinson, '14), Agaricus Rodmani (Atkinson, '15), 

 Armillaria mellea (Atkinson, '14), and Stropharia ambigua (Zeller, 

 '14). 



3. The stem fundament is outlined first, followed by the pro- 



