MacDougal. — Symbiotic Saprophytism. 5 
Fungus of Lister a cordata resembles Nectria as originally 
described by Wahrlich on Vanda . It is to be seen that the 
greater number of mycorhizal Fungi remain to be identified. 
All known species may be included in the Oomycetes, 
Pyrenomycetes, Hymenomycetes, and Gasteromycetes. No 
attention has been paid to this phase of the subject in 
the work described in this paper, though reproductive 
bodies resembling Penicillium were observed on the roots 
of Pterospora andromedea . 
It is apparent that the mere presence of the Fungus in 
or on the root of a higher plant by no means constitutes 
a mycorhiza, since in a great number of cases the relation 
is undeniable parasitism. Rees and Fisch call attention 
to the fact that the relation of a Fungus to the root of 
a specific plant is not always a fixed one (32). The chemical 
interchange may be so evenly balanced during a part of the 
season, or during a part of the lifetime of the Fungus or of the 
higher symbiont, as to constitute a symbiosis ; but in other 
stages the presence of the lower form may result in positive 
damage or disadvantage to the higher plant. Thus Macfarlane 
concludes that the mycorhizal PTingus of Philesia is an 
ultimate disadvantage to the plant, since it hastens the death 
of the absorbing organs. The experimental tests of the 
identity and relationship of the Fungus and the higher 
plant have been the following methods : cultural examina- 
tion of mycorhizal Fungi ; formation of mycorhiza by the 
culture of Fungi on the roots of trees; and the growth of 
symbiotic plants in sterilized soils. As a general result 
of such experiments, it may be stated that any higher plant 
may form mycorhiza with only one or two species of Fungi ; 
and that nearly all hemisaprophytes may develop normally, 
though with some decrease of stature, without the presence 
of the fungal symbiont. This is especially true of the forest- 
trees. On account of the great elasticity of the various 
factors to be considered in symbiotic saprophytism, it is to 
be seen that no definite conclusions may be drawn as to the 
relations of the attached plants without a general considera- 
