528 
AMERICAN JOURNAL OF BOTANY 
[Vol. 9, 
Summary 
1. Fresh buttons of Agaricus campestris fixed in the standard fixing 
agents show shrinkage and tearing of the fundamental tissue within 6 to 
24 hours after fixation. 
2. Fresh and dead carpophores of A. campestris studied show no primary 
annular gill cavity but a series of arches or gill cavities between each pair 
of gills with the trama tissue continuous with the hyphae of the pileus and 
of the stipe rudiments. There is no one general annular gill cavity but a 
number of interlamellar cavities similar to those found in the Coprinus 
species. 
3. Spores of Coprinus ephemerus and C. stercorarius sown on dung or 
bean agar produce carpophores within 10 days after the inoculation is made. 
4. The early stages in the development of the carpophore Anlage in 
these species is similar to that in C. micaceus. The early stages in the 
differentiation of the carpophore of these species are similar, up to the time 
of the development of the lamellae, to those of other types of agarics already 
described. The development of the lamellae of C. ephemerus and C. ster- 
corarius is similar to that described by me for C. micaceus. No general 
annular gill cavity is formed. 
5. The primordium of the hymenium arises as pockets of palisade cells 
with the ends of these cells pointing downward. As they increase in number 
they form a small arch, enclosing thus an interhyphal space between their 
free ends. This interhyphal space is the beginning of a gill cavity. The 
palisade cells forming the vertical walls of the arch are the rudiments of 
the adjacent hymenia of two gills. The vertical plate of hyphae between 
two adjacent arches constitutes the rudimentary trama, which is continuous 
with the hyphae of the stipe below and of the pilear fundament above. 
The young gill in its earliest stages of development is composed of the 
tramal cells together with the adjacent vertical walls of two arches. 
6. Secondary or short gills arise in a manner similar to that of the 
primary gills. As the pilear rudiment increases in diameter, the distance 
between two adjacent rudiments of primary lamellae of the margin becomes 
greater and greater. A new pocket of palisade cells is intercalated at the 
margin of the pileus between two pockets of cells already formed and which 
are already open near the stipe. A cluster of new tramal hyphae is also 
formed which is fixed and continuous between the stipe and the pileus, as 
are the trama cells of the primary gills. As the palisade cells of the new 
pocket and the cells of the already formed adjacent pocket increase, two 
small arches are formed, separated by the newly formed trama and the 
adjacent hymenia. The trama and the adjacent hymenial surfaces con- 
stitute the short gill. This divides the former gill cavity into two. 
7. The short gills are attached to the stipe fundament from the very 
beginning and do not grow downward between two old gills. 
Columbia University 
