AND SPORES IN AGARICUS CAMPESTRIS. 171 
matter of soil, climatic conditions, &c.) than is the case with 
plants cultivated in mushroom-houses. Thus it may be possible 
to reconcile the conflicting statements of Massee and Hesse, both 
of whom are apparently writing of the mushroom growing in a 
wild state. 
For purposes of comparison a number of species belonging to 
other genera and subgenera were examined, all of which uniformly 
possessed four sterigmata. Amongst the species of the Hymeno- 
mycetes which have been described up to the present as usually 
bearing only two sterigmata on each basidium are Agaricus 
(Psalliota) campestris, Ag. (Psalliota) sylvaticus, Ag. (Mycena) 
corticola, Ag. (Mycena) hiemalis, Ag. ( Naucoria) tenax, Hypochnus 
bisporus, Pistillaria micans, Craterellus cornucopioides, and the 
genera Guepinia, Calocera, and Dacryomyces. 
EXPLANATION OF PLATE 10. 
Fig. 1. Portion of the hymenium of Agaricus campestris, showing basidia 
bearing spores of different ages. One basidium is shown bearing three 
, nearly ripe spores, and another bearing four very young ones. 
Fig, 2. Basidia in longitudinal section, with spores 2z situ. 
Fig. 3. Basidia in transverse section (diagrammatic), showing the arrangement 
of the sterigmata. 
All figures are magnified 1200 diameters, and were drawn under the Abbé 
Camera Lucida, 
LINN, 
JOURN.—BOTANY, VOL, XXXIII. o 
