Conard: Secotium Agaricoides 
95 
diameter, and 4 mm. tall and 3.5 mm. in diameter, were collected 
in 1912. All were cut open, fixed in chromo-acetic acid, sectioned 
in paraffin 3^, 6f, or 10 microns thick, and stained with various 
stains. The best results were obtained with Haidenhain’s iron- 
alum-haematoxylin. The mature specimens were dry when col- 
lected and were stored in boxes. 
Development . — The youngest specimens are nearly globular, 
white, and smooth. Then comes a “ button ” stage, with the 
upper portion slightly larger than the stalk and the surface still 
smooth. Later, the fertile portion increases greatly in height and 
diameter, leaving the free stalk as a mere basal projection. The 
superficial brown scales of the peridium appear only when near 
full maturity. The spores are fully mature while the trama, perid- 
ium, and stalk are still fleshy. The old specimens, at least in our 
climate, dry up and do not putrify. 
The Peridium . — Sections of the 3.5 mm. specimen show an in- 
definite outer layer of loosely woven hyphae surrounding a dense 
mass of closely packed threads (PI. 157, fig. i). Within this glob- 
ular body and near its summit a ring of deeply-staining tissue is 
already found. This is the fundament of the hymenophore. In 
older specimens, the hymenophore hyphae take a distinctly radial 
and longitudinal direction and form a thick and well-marked zone. 
Between this layer and the outer webby portion, the hyphae are 
less crowded and take a paler stain. Their course is predomin- 
antly longitudinal (radial). This layer is continuous below with 
the substance of the stalk. At this stage (9 mm. in diameter), the 
outer webby layer is more prominent and continues down upon 
the stalk of the “ button.” Soon after this, however, the layer 
completely disappears. The mature peridium shows only a broad 
layer of longitudinal hyphae, with a thin superficial layer of 
crushed and withered threads. 
The outermost loose layer of the young plant (PI. 157, fig. 5, 6) 
agrees in structure and position with the universal veil or blema- 
togen of the evolvate agarics {Agaricus, Atkinson 1906, 1914a; 
Armillaria, Atkinson 1914b; and Stropharia, Zeller 1914). The 
second layer forms the bulk of the tissue of the peridium. 
The mature peridium is fleshy to leathery in texture. It is about 
2 mm. thick on the sides of the body, thinning below to nothing 
