The Biology of Polyporus Pargamenus Fries 87 
as a control. At the beginning both blocks of wood bore 
partially formed sporophores on the sides and under surfaces, 
but on the tops the mycelium was just appearing through the 
lenticels and had not begun to differentiate into the parts 
of a sporophore. In a few days a floccose growth appeared 
from each of the lenticels of the block kept in darkness. Soon 
after this these hyphal growths assumed the form of loosely 
interwoven bosses. In the ease of the block kept in the light 
a slow scant growth was made by the mycelium but it was 
of a compact leathery nature and never loose and fluffy as 
was the growth made in the dark. In addition the mycelium 
which developed in darkness made a much greater and more 
rapid growth than that which developed in the light of the 
laboratory. It was evident that the absence of light stimu- 
lates the mycelium to a much greater vegetative erowth than 
otherwise would oceur. After a month the my yeelium put 
forth from each lenticel, which at first appeared as a fluffy 
boss, became more or less compacted and spongy in consist- 
ency. In no case, however, did any sporophores form on the 
block kept in the dark. Even the embryonic ones originally 
present failed to develop farther and became covered over 
by the outgrowth of mycelium. On the block kept exposed 
to the light of the labor atorv, however, the mycelium devel- 
oped Mi Gud aiuiber of Smobrieate sporophores which shed 
copious quantities of spores. 
This experiment points to ight as the controlling factor 
in sporophore production, although no account has been taken 
of the combined action of light and gravity. Experiments 
were made on a similar form with “this idea in view by 
Bayliss (1908) as follows: -Two small branches bearing 
normal sporophores of Polyporus (Polystictus) versicolor 
were secured. One branch was attached horizontally to a 
clock clinostat and the other used as a control. The appa- 
ratus was set up outside of the laboratory window where the 
branches had the advantages of ordinary atmospheric con- 
ditions and could be assured of a continuous supply of moist- 
ure by means of a dripping device. Never, however, during 
the several months’ duration of the experiment did a typical 
