346 
MICHAEL LEVINE 
pestris by a study of A. arvensis and A. comtulus. In a longitudinal 
median section of A . arvensis the first indication of any internal differ- 
entiation in the carpophore primordium is the appearance of two light 
areas. These represent the beginning of the annular gill chamber, thus 
differing from ^. campestris. Atkinson (i 9142) in a preliminary report 
on the development of Amanitopsis vaginata and Lepiota clypeolaria, 
holds with Fayod that the primordium of the pileus is the first to 
develop in the young carpophore. In Amanitopsis vaginata he now 
finds that the trama is continuous with the tissue of the pileus and the 
surface of the stipe. There is no internal annular gill cavity. In 
Lepiota clypeolaria as in Armillaria mellea (1914^) Atkinson describes 
the first appearance of the hymenium as two masses of hyphae densely 
stained in the upper part and on opposite sides of a longitudinal section 
of a young carpophore. The annular gill chamber is formed and then 
radial plates of hyphae from the primordium grow into the gill chamber 
forming the lamellae. 
Miss Allen (1906), one of Atkinson's pupils, has studied a number 
of species of Hypholoma and establishes the endogenous origin of the 
gills in the several species as against the claims of Hartig for Armillaria 
mellea. Fischer (1909) studied the morphological development of 
Armillaria mucida Schrad. but adds nothing to our understanding of 
the origin and development of the lamellae and the hymenium. 
Beer (191 1) also confirms the endogenous origin of the hymenium 
in three species of Agaricaceae. Zeller (1914) studied the development 
of Stropharia amhigua using young buttons collected in the field. He 
describes the differentiation of the young carpophore as consisting 
first in the formation of an endogenous annular rudimentary hymen- 
ium. He claims that the pileus is formed later by an upward growth 
of hyphae from the outer edge of the hymenium primordium so as to 
form an internal inverted cup-shaped structure below the upper 
portion of the carpophore. The gill chamber is formed by the sagging 
of the tissue below the hymenium primordium. The lamellae are 
formed by the downward growth of radial hyphae. The apical cells 
of these hyphae spread laterally thus forming a groove along the edge 
of the gill. The hymenial hyphae arise as branches near clamp 
connections in the subhymenium but gives no figures in support of 
his statement. Zeller believes that the formation of the hymenium in 
all annulate agarics precedes that of the pileus primordium while in 
other agarics the pileus primordium develops first. Zeller does not 
