248 BOTANICAL GAZETTE [ocTOBER 
do not show the early stages of organization and differentiation, and 
GoEBEL’s figures (jig. 89, J. c.) of the section of the young fruit bodies 
are made after the young pileus is differeatiated from the stipe. No 
evidence is given that this text book account is the result of original 
investigation, and it is more likely that GorBet here is relying on 
the early account given by DEBary, and the still earlier one given 
by HorrMann cited above. 
In a similar way, in describing the early stages of development 
of Agaricus campestris,7® I have followed DEBary’s later account 
as follows (p. 7): “At the same time a veil is formed over the gills 
by threads which grow from the stem upward to the side of the but- 
ton, and from the side of the button down toward the stem to meet 
them. This covers up the gills at an early period.” Aside from 
the extensive work of Fayop in 1880,'® little work seems to have 
been done on the development of the young sporocarps of the Agar 
caceae since the publication of DEBary’s work in 1887. 
In January r905 an excellent opportunity presented itse 
obtaining material in the required stages of development. Cultures 
had been made in boxes in the greenhouse of the commercial variety 
of Agaricus campestris known as Columbia, sold by the Pure Culture 
Spawn Company of Missouri, In many cases large numbers of 
young carpophores were formed at the surface of the substratum 
which were clean and in excellent condition for study. Preliminary 
examinations were made by freehand sections, and by staining a 
order to determine the age and size of the fruit bodies which shoul 
be prepared. In fruit bodies about 1™™ in diameter there don no 
evidence of a superficial annular furrow nor of any internal differen 
tiation, Fruit bodies, therefore, from 1™™ to 4™™ were selected, 
fixed in chromo-acetic acid, imbedded in paraffin, microtomed, 4” 
stained, some in acid fuchsin and some in methyl blue. 
The youngest stage is the primordium of the carpophore, 4 — 
tricately 
of 
lf for 
geneous body composed of slender uniform dense hyphae, 1” “ 
interwoven, and surrounded by a very thin layer of hyphae 
*8 Studies in American fungi, mushrooms, edible, poisonous, et» eae 
Ithaca, N. Y., 1900; 2d ed. 1901; and New York 1903. 
19 Prodrome d’une histoire naturelle des Agaricinées. Ann. Sci. 
Q9:181-411. pls. 6-7. 1889. 
Nat. Bot. VII. 
