32 MacDougal. — Symbiotic Saprophytism. 
phytes have centered in the facts obtained from the study 
of Monotropa , M. Hypopitys in particular. It will be of 
interest to recall that three distinct theories have been 
advanced at different times in explanation of the nutritive 
system of this group. Unger, as a result of his investigations 
in 1840, concluded that Monotropa was a parasite upon the 
roots of trees ( 40 ). Various contradictory and indeterminate 
results were brought forward by a number of workers in the 
next forty years, until Kamienski demonstrated in 1881 ( 19 ) 
that it was not parasitic, and later gave an inclusive history 
of its development with careful attention to the relation 
of the higher plant to the mycelium sheathing the roots (20). 
After Kamienski had proved that Monotropa has no nutritive 
contact with other seed-forming plants, Frank advanced 
the opinion that it was actually parasitic upon the Fungus 
attached to the roots ( 9 ) ; a theory which is also supported 
by Kerner ( 21 ), who says, 4 Since it is quite destitute of 
chlorophyll, and its aerial stems and leaves display no 
trace of stomata, the possibility of creating organic matter 
and of at all adding to its substance by means of aerial 
parts is excluded.’ It may be said, in comment, that no 
actual proof is at hand to show that no advantage does 
accrue to the Fungus by its association with the higher 
plant. The possibility is by no means excluded that the 
shoot may absorb heat or light and use such energy in 
the promotion of metabolic processes, the products of which 
might be available for the Fungus. The union of the cells 
of the Fungus and the higher plant is of such an intimate 
nature that the assumption of no interchange of material 
is not justifiable. The mere mechanical lodgement of the 
Fungus on the roots of the other plant may be of benefit to it. 
The argument from the structure of the higher plant is 
invalidated from the fact that while the general relation 
of the Fungus and the higher plant is the same in Monotropa 
and Pterospora , the latter is furnished with stomata and other 
mechanisms for gaseous interchange. The symbiosis of the 
Monotropeae and the associated Fungi must be regarded as 
