THE ORIGIN AND DEVELOPMENT OF THE LAMELLAE IN 
COPRINUS MICACEUS 
Michael Levine 
The question as to the origin and method of development of the 
gills in the hymenomycetes still remains unsettled. Certain stages 
are well known and have been many times described and figured and 
certain general conclusions are widely accepted. For example, that 
in many forms the gills arise endogenously and that the relative posi- 
tions of the stipe, pileus and hymenium are the same in the undiffer- 
entiated button as in the adult. On the other hand, the question as 
to the method of origin of the gill cavity, the direction of growth of 
the gill rudiments and their relation to the stipe and pileus, the differ- 
entiation of trama and hymenium, etc., have never been clearly and 
adequately described. The older literature has been reviewed by 
Atkinson (1906) and others, and I will note only such points as bear 
especially on my own observations on Coprinus micaceus. 
Schmitz (1842) describes the gill cavity in Agaricus Bulliardi as 
an annular cavity separating pileus and stipe. The layer of hyphae 
connecting the outer margin of the pileus and stipe he called the veil 
or cortina. It is not clear what he means by veil as compared with 
the peripheral layer found in Coprinus micaceus. Schmitz proposed a 
theory of development for all pileate species of. fungi according to which 
the organ nearest the substratum in the mature form is the structure 
first to arise, thus the mycelium precedes the stipe and the stipe the 
pileus while the hymenophore is formed last. Hoffmann's (1856) 
description of the development of the carpophore lies at the basis of 
many of the current accounts of the method of formation of the pileus 
and hymenium. He describes the young buttons of Agaricus cam- 
pestris as small spheres which elongate owing to the growth of the 
interior cells perpendicularly upward. The terminal cells now grow 
out laterally and then turn abruptly downward. The ends of these 
hyphae form the lamellae primordia. In a later paper (i860) he 
described sixteen further species of Agaricaceae and still later (1861) 
he described the development of Coprinus fimetarius. Hoffmann 
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