222 BOTANICAL GAZETTE [serremaun 
Sequence of plant parts 
The relative time of origin of the primordia of the basidiocarp is 
of some historical interest. Fries (17), influenced perhaps by the 
preformation theory, still in vogue in his time, believed that all 
the parts, pileus, stem, and hymenophore, although indistinguish- 
able, existed already formed in the young fruit body and unfolded 
simultaneously. Scumirz (24) held that a successive formation of 
new parts occurred; that the development of new parts rose 
upward just as gradually as in the higher plants, so that those 
stariding higher came into evidence later than those below; and 
that therefore the matrix developed before the stipe, the latter 
before the pileus, and the latter before the hymenium. Later, 
Fayop (15) formulated a general law to the effect that the first 
part to be differentiated is always the pileus primordium. 
More recent work has shown that no general rule can be laid 
down as to what primordium shall have precedence in differentia- 
tion. In Agaricus campestris (2), A. arvensis (3), A. rodmani (8), 
Armillaria mellea (4), and Siropharia ambigua (25), the hymeno- 
phore primordium is differentiated first. In Hypholoma sub- — 
lateritium (x), H. fasciculare (11), and Amanitopsis vaginata (7) the | 
. pileus area is first outlined. The formation of the stem fundament 
is the first differentiation to take place in Lepiota cristata and L. 
seminuda (10), several species of Cortinarius (14), Rozites gongy- 
lophora ids ~ the 3 species of Pholote described. : 
Even in the same species y occur as to the relative : 
of the different t primordia. ATKINSON (10) has" 
shown this to be eine § in Agaricus arvensis (3) and Lepiota 
: time of 
clypeolaria (6). In P. flammans a would appear that the funda oe 
ment of the pileus i nen 
a primordium, and this may be true of the other two ‘species: a 
ih all 3 species, however, the er of ~ sities o 
