CHAPTER II.—DIFFERENTIATION OF THE THALLUS—-MYCELIAL STRANDS. 27 
the cushion, and breaking through the rind of the parent-strand grows in the manner 
which has already been described. Its final medullary hyphae become continuous 
with those of the medulla of the parent-strand. Schmitz first observed that, at 
least when old strands are cultivated in a damp chamber, the place of every future 
branch is indicated some days before its emergence by the appearance of a floccose 
tuft of hyphae 4—1 mm. in size, arising partly beneath, partly also according to 
Hartig out of the surface of the parent-strand, which decays and disappears as 
the branch is formed. 
The stronger subcortical strands and the membrane-like expansions in the 
living tree are said by Hartig to be similar to the subterranean ones just described in 
structure and development, except in respect 
of certain differences arising from difference 
of form, the somewhat smaller masses of 
tissue, and the fainter tinge of brown on 
the outer layers of the rind or the entire 
absence of that colour. Very delicate myce- 
lial membranes and slender tufts of ramifying 
branches, which frequently arise on the edge 
of the larger mycelial body, have a more 
simple structure and consist only of hyphae 
of the rind. There is one important pecu- 
liarity in all these strands and expansions, 
that the numerous hyphae which stand out 
like hairs from the surface force their way 
into the tissue of the rind and wood, and 
spread and ramify there, and are organs by 
which the Fungus takes up its food. They 
often form bladder-like swellings in the 
tracheides of the pine-wood which they 
decompose, reminding one of the inner 
layers of the rind of the strand, and their 
number in the tracheides may be so large 
as to fill them with a tissue of bladder-like r 
nn tasted ice ote ge se goal ani tae 
Brefeld has completed our knowledge of der egg cern medullary hyphae 4 grow as 
the life-history of the mycelium of Agaricus 
melleus by growing it from spores in an artificial nutrient solution (decoction 
of plums), A delicate branched radiating primary mycelial hypha was developed 
in about eight days from the germ-tube which issued from the spore cultivated 
on a microscopic slide. Thick tuft-like branchlets from single branches of the 
hyphae or from several adjacent ones then appeared in the centre of the circular 
expansion which was some millimetres in size; these tufts raised themselves erect 
and became united together into clews as large, according to the figures, as a 
good-sized pin’s head, after the manner of the sclerotia to be described below in 




* R. Hartig, Die Zersetzungserscheinungen d. Holzes, Pp. 59. 
