254 BOTANICAL GAZETTE [APRIL 
branch were removed. It was therefore certain that if any fruit- 
bodies appeared, they had developed from their earliest stages on 
the klinostat. The precaution is important, since the fruit-bodies of 
the Agaricaceae are completely differentiated during their earliest 
stages of growth. Beyond these stages the parts, therefore, can no 
longer be subject to formative stimuli. On several of these sticks 
the fruit-bodies developed within about a month. They appear as 
small outgrowths resembling simple forms of Clavaria, and attain a 
length of about 1°™. Early in their development a cup-like depres- 
sion appears at the summit, and within this the rudimentary lamellae 
are formed, radiating from the center. The fruit-bodies at this 
stage have the form of a short trumpet about 1°™ long. The out- 
side has the characteristic appearance of the dorsal surface of the 
normal fruit-body. By subsequent growth the margin expands 
uniformly at first, but later unequally, so that the resulting fruit-body 
is a lobed disk, 2-3°™ in diameter, and stalked at the back. The 
curious fact brought out by this experiment is that the lamellae 
develop on the inner side of the trumpet- or funnel-shaped fruit-body. 
The pileus, therefore, appears to be attached at the back, with the 
lamellae developing on the morphologically upper side. 
To study the effect of gravity on some more specialized form, 
dung-cultures were set up for Coprinus. These were continually 
rotated so that the entire development of the fungi from the germina- 
tion of the spore to the maturation of the fruit-body took place on 
the klinostat. The primordia of the fruit-bodies were thus at no 
time subject to the normal influence of gravity. Several crops of 
Coprinus developed on the cultures, but the fruit-bodies were 
normal in every way. Their direction of growth was perpendicular 
to the substratum, the actual direction being horizontal, since the 
pots were rotated on the horizontal axis of the klinostat. 
The experiments with the foregoing three types show the existence 
of a marked difference in the degree to which the form of these types 
is modified by or depends upon the stimulus of gravity. Of the 
plants studied, Polystictus is the more plastic, and is consequently 
more influenced by gravity. Here the differentiation of the fruit- 
body into the sterile dorsal and fertile ventral surface depends on the 
direct or indirect action of gravity. In Schizophyllum the tissue 
