153 MR. R. H. BIFFEN ON THE 
from those grown in the light, but the growth of the pileus seems 
to be inhibited to a certain extent; at any rate its appearance is 
delayed, and eventually slender stipes, an inch or an inch and 
a half high, are produced bearing only a minute pileus. 
As it seemed possible that the cultures in plugged test-tubes 
might suffer from being insufliciently aerated, others were put up 
in U-tubes and flasks through which a stream of moist, filtered 
air was drawn by means of an aspirator. In these cultures the 
external mycelium was a little thicker, but the sporophores, whieh 
were later in forming, were no larger than those in the plugged 
tubes. In order to see whether the steam-sterilizing caused any 
washing out or destruetion of nutritive substances in the wood, 
cultures were also made on blocks dry-sterilized by being heated 
as before, but without wetting the cotton-wool plugs at the bottom 
of the tubes until they were ready for infection. When com- 
pared with the wet-sterilized cultures, infected at the same time, 
however, no differences could be detected. In spite of this it is 
evident that some essential nutrient materials are dissolved out, 
for sporophores develop in abundance on the wet plugs of the 
wet-sterilized tubes, and none develop on the plugs of the dry- 
sterilized ones. The experiment only shows, then, that the amount 
dissolved is slight, and not sufficient to check the growth of the 
fungus. 
Further, eultures were made on wood extracted with a boiling 
5 per cent. solution of caustic potash, to remove xylose-yielding 
bodies, or with a 5 per cent. solution of hydrochlorie acid to re- 
move hemicelluloses. These solutions were then thoroughly 
washed out with distilled water, which was changed at frequent 
intervals for a week. In both sets of tubes the growth of the 
mycelium was extremely slow, and so far no sporophores have 
been produced (infected for 12 weeks). 
Mieroscopie examination of the external mycelium shows that 
it is septate, with numerous clamp connections.  lts mealy 
appearance is due to the large number of oidia-chains formed. 
Longitudinal sections of the mature sporophore show a cortex 
bearing several forms of hairs, a medulla composed of loosely 
woven hyphe, and a hollow stipes. If the sections are stained 
in eosin, or better in fuchsin-methyl green, a system of hyphe, 
having a general resemblance to laticiferous cells, is differentiated 
by staining more deeply than the surrounding tissue. Its 
