THE LAMELLAE IN COPRINUS MICACEUS 
345 
many other species of the Agaricaceae the hymenium is endogenous 
in origin. 
Brefeld (1877) maintained that the carpophore of the Coprini 
arises from a single cell. This cell is not specially differentiated and 
Brefeld's main interest was in maintaining that there is no morpho- 
logical equivalent of the ascogonium of the Ascomycetes in the Basidio- 
mycetes. The carpophore anlage is a mycelial hypha which gives rise 
to a number of branches which intertwine, forming a small mass of 
coiled hyphae. This mass increases in size and internal differentiation 
sets in. The whole carpophore is covered by a loose layer of globular 
cells which Brefeld holds is morphologically equivalent to the volva of 
the Amanitas and differs only in that in the latter genus the structure 
is more compact. Brefeld held that the lamellae arise as compact 
bundles of parallel hyphae, each of which has apical growth. Nu- 
merous branches are produced which turn to the right and left to form 
the hymenium. The growth of the lamellae results finally in the 
adhesion of their edges to the surface of the stipe. He found in large 
carpophores of Coprinus stercorarius that there are about one hundred 
and fifty lamellae of which one third are primary, two thirds secondary. 
V. Fayod (1889) on the basis of studies on a long series of forms 
discards Hoffmann's conception of the method of development of the 
pileus and hymenium. Fayod held that in the upper portion of the 
spherical button a layer of dense hyphae is differentiated which has 
the form of an inverted bowl. This dense inner portion Fayod calls 
the couche piUogene. He admits that the pileus widens by lateral 
growth of the hyphae of this pileogenous mass. 
Practically nothing further was done during the fifteen years fol- 
lowing Fayod's work, but in 1906 Atkinson again took up the question 
as to the mode of differentiation of the carpophore, especially the veil 
and lamellae as found in Agaricus campestris var. Columbia and A . cam- 
pestris var. Alaska. The gill rudiments appear first in a longitudinal 
median section of the young caropophore as two deeply stained areas. 
These areas represent the cross section of a heavily stained horizontal 
ring composed of hyphae which have a very dense protoplasm. This 
annular layer is the hymenial primordium. The hyphae below this 
structure rupture and an annular hollow cavity, the gill chamber, is 
thus formed. The lamellae are formed by a downward growth of 
hyphae from the hymenial primordium into the gill chamber. In 
(19149 Atkinson confirmed his observations made on Agaricus cam- 
