Nov., 1922] LEVINE LAMELLAE IN AGARICUS CAMPESTRIS 5II 
Columbia and Alaska. Atkinson claims that the gill rudiments appear first 
in a longitudinal median section of the young carpophore as two deeply 
stained areas. These areas represent the cross section of a heavily stained 
horizontal ring which is the primordium of the hymenium, composed of 
hyphae which have a very dense protoplasm. The hyphae below this 
structure rupture, and an annular hollow gill cavity is formed. The 
lamellae are formed by a downward growth of hyphae from the hymenium 
primordium into the gill chamber. These observations were confirmed by 
Atkinson on several other species of Agaricus. 
The author of the present paper pointed out (1914) that the origin of 
the gills in agarics was not yet clearly understood. It was then shown 
that in the development of the lamellae of Coprinus micaceus, the young 
hymenophore arises at or near the lower surface of the pileus primordium 
in a manner similar to that described for a number of agarics by Hoffmann 
(i860), and that it appears in a vertical section of a young carpophore as 
two densely staining areas of palisade cells, placed to the left and right 
above the center of the young carpophore. 
I pointed out further that the development of this annular primordium 
of the hymenophore consists in further elongation and, at the same time, 
specific orientation of these palisade cells. This results in the formation of 
a series of arched interhyphal spaces or primordia of gill chambers, while 
the adjacent palisades become the gill rudiments. The point which was 
emphasized was that the hymenial elements are formed over the arched 
surface of the interhyphal spaces, rather than on the edges of gill ridges 
extending downward into an annular gill cavity. In other words, the gill 
rudiments at this stage are continuous above and below with the funda- 
mental tissues of the stipe and pileus. While De Bary (1887) figured this 
condition in the development of young buttons of Coprinus, he failed to 
point out its significance. The report of my observations on C. micaceus 
appeared about the same time as Atkinson's (1914c) description of the 
development of the carpophore of Amanitopsis vaginata. No primitive 
annular gill cavity is formed in this species. The young lamellae extend 
from the pileus fundament to the stipe region. In this respect the develop- 
ment of Amanitopsis species is like that of Amanita described by De Bary 
and Brefeld and like that of Coprinus micaceus described by me, but, 
according to Atkinson, is unlike the development of all other agarics. The 
growth at the margin of the pileus primordium is accompanied by a con- 
tinuation of the differentiation in the fundamental tissue. 
This development in Amanitopsis is identical with the stages found in 
plants of Coprinus micaceus and of other species of Coprinus that I have 
studied. But for the bulbous base of the stipe region and the thickened 
volva, sections of Amanitopsis and of Coprinus resemble each other very 
closely [see figures 83, 92, and 93, Plate XXXIV, and compare them with 
Atkinson's (1914c) figures 10, 13, and 14]. 
