262 BOTANICAL GAZETTE [OCTOBER 
them, and that hybrids between species were very commonly found 
where cystidia and spores from adjacent species fell to the ground, 
commingled, and brought about cross fertilization. But the last 
word may not yet have been said with reference to the possibility of 
a fertilization prior to or during the early stages of the organization 
of the primordium of the carpophore, like that proposed by OERSTED 
(l. c.) for Agaricus (Crepidotus) variabilis, or in some closely related 
manner. 
However, the propagation of forms by spawn which is not obtained 
from the spores, as is practiced by DuccGar,35 would seem to be 
equivalent to vegetative propagation or budding, and thus might be 
of advantage in maintaining constancy in varieties, since they would 
not be subject to cross fertilization, though it is still a question if 
fertilization and cross fertilization take place in the Agaricaceae. 
If it does not, or if some process equivalent to it, especially cross fer- 
tilization, does not take place, the Agaricaceae, and in fact the 
Hymeniales, would be especially free from the production of hybrids, 
and the constancy of species or varieties arising by mutation would 
be correspondingly favored. In a numberof species there are indica-" 
tions that mutation is now going on, or that these species have recently 
passed through a period of mutation, and some of these apparent 
mutants appear to be quite constant, On the other hand, there ar 
many species which show great fluctuating variability due to varying 
conditions of food supply, moisture, substratum, etc. 
CoRNELL UNIVERSITY, 
t x. 
DESCRIPTION OF PLATES VII-XI. 
Photomicrographs with Zeiss microscope except fig. II; plate holder 
from object on slide; photomicrographs and photographs by the author. 
PLATE VII. 
360™ 
. m 
Fic. 1. Young carpophore, var. Alaska, undifferentiated; oc. 2, obj. 16°" 
Fic. 2. Same as fig. 1, but with oc. 4, obj. 16™™. aia tek 
Fic. 3. Young carpophore, var. Columbia, with primordium of hymenium 
earliest stages of endogenous origin; oc. 2, obj. 16™™. 
35 Duccar, B. M., The principles of mushroom growing and mushroom? ne 
making. U.S. Dept. of Agr., Bureau of Plant Industry, Bull. 85. PP- go. Ps: 
1905. 
