Mycologisches Centralblatt, Bd. IV, Heît 3. 
, Ausgegeben am 21. April L914. 
The development of Armillaria mellea. 
By Geo. F. Atkinson, Ithaca N. Y. 
(With 2 plates.) 
In 1861 H. Hoffmann described the structure and partial develop¬ 
ment of Agaricus melleus 1 ). While he studied and described quite small 
specimens, they were too far advanced to determine the origin and dif¬ 
ferentiation of the different parts of the plant, and whether the hyménium 
was of endogenous or exogenous origin. 
R. Hartig in 1874 2 ) made a more careful study of the development, 
and also determined that the fruit bodies were organically connected with 
the rhizomorphs known as Rhizomorpha fragilis , R. subcorticalis , etc. 
As his illustrations show he had access to a large number of very young 
carpophores directly connected with rhizomorphs free in the soil, but also 
breaking out from underneath the bark of roots and the bases of tree 
trunks. He states that the development of Armillaria mellea in essen¬ 
tial points differs completely from that described by de Bary in 1866 3 ) 
for Agaricus campestris. In the very early stages he says it develops 
in exactly the same way as the forms without a veil (gymnocarpous 
forms), that is, the young carpophore is first differentiated into a stem 
and pileus part by the formation of a superficial annular furrow which 
marks the primordium of the hyménium. In the beginning this is com¬ 
pletely open to the outside, but is enclosed by the subsequent downward 
growth of hypliae from the edge of the pileus and the upward growth 
of hyphae from the stem, which meet and interlace, thus bridging over 
the annular furrow. Although Hoffmann 4 ) and later de Bary (1. c. 68) 
had correctly described the development of Agaricus campestris , Hartig 
declared his conviction, that, judging from de Bary’s figures, the formation 
of the veil in A. campestris agreed in all respects with that of Armillaria 
as described by him. Influenced by the weight of Hartig’s authority, 
1) Hoffmann, H., leones Analyticae Fungorum, Abbildungen und Be¬ 
schreibungen von Pilzen mit besonderer Rücksicht auf Anatomie und Entwicklungs¬ 
geschichte, 1861. Armillaria on pages 90 — 92, PI. 21, figs. 1—17. 
2) Wichtige Krankheiten der Waldbäume usw., Agaricus (Armillaria) 
melleus L., p. 12—42, pis. 1, 2, 1874. 
8) Morphologie und Physiologie der Pilze, Flechten und Myxo- 
my c eten, p. 68—70, Fig. 26, 1866. 
4) Hoffmann, H., Pollinarien und Spermatien bei Agaricus (Bot. Ztg. 
14, p. 137—148, 153—163, pl. 5, 1856). See also Beiträge zur Entwicklungs¬ 
geschichte und Anatomie der Agaricineen (Bot. Ztg. 18, p. 389—395, 397—404, 
pis. 13—14, 1860) and Icônes Analyticae Fungorum, Abbildungen und Beschrei¬ 
bungen von Pilzen mit besonderer Rücksicht auf Anatomie und Entwicklungsgeschichte, 
p. 1—105, pis. 1—24, 1861). 
Mycologisches Ceutralblatt, Bd. IV. 
8 
