34 Mac Doug at. — Symbiotic Saprophytism. 
accumulating reserve food, and finally developing the enormous 
reproductive shoots. In no other manner does it seem possible 
to account for the great discrepancy between the root-system 
and the shoot. The formation of reproductive branches 
continues for two or possibly three seasons, and then the 
entire plant dies. During the winter season the old shoots 
die away, but in some instances remain attached to the 
clump. As a matter of fact the stems begin to dry and 
harden with the ripening of the seeds in August. The 
extensive degeneration of the root-system without a corre- 
sponding alteration in the shoot, is a phase of this species 
for which no satisfactory explanation is offered by the facts 
at hand. It certainly has the appearance of tending to the 
rapid extinction of the species. 
The Roots . The absorbing organs of Pterospora consist of 
several primary roots, attaining a length of 9 to 20 mm., 
giving off a number of club-shaped rootlets 6 to 9 mm. long 
which in turn show short cylindrical or flattened branches of 
the third order. The roots and branches intertwine to form 
a compact globoid mass the boundaries of which are sharply 
defined, as no branches or tips project beyond the general 
outline. The apices of rootlets on emerging from the mass 
appear to curve back toward it, in a manner indicative of 
chemotropic reaction. A section of the mass shows the 
tissue of the roots separated by thin streaks of mycelia and 
humus. The slice will be quite firm and coherent both in 
living and alcohol-material, having the consistency of a potato- 
tuber. The sections of the different roots do not separate 
entirely even when made thin enough for microscopical 
examination. The amount of humus included in these layers 
is small and quite insufficient for the needs of the plant, but 
it is to be seen that the hyphae ramify thickly through the 
soil in all directions. The arrangement of the roots permits 
no clamping action on the substratum, and hence these organs 
may be said to have lost their primitive function of fixation. 
Kamienski found that the finer branches of the roots of 
Monotropa Hypopitys extend out into the soil a distance of 
