THE FUNGUS-ROOT (MYCORRHIZA). 185 
been brought down by the hooked processes. It is possible to 
find scattered portions of the hyphal threads that were around 
and between the two styles at different points along the hypo- 
cotyl. The fungus is not difficult to identify as such. It hasa 
diameter of 2 to 2.5 u, is frequently septate, with cells 15 to18 wu 
in length. It is stained in a few minutes by a solution of cotton 
blue in lactic acid. The fungus has not so far been traced below 
the surface of the soil except in small quantity. The occasion 
is not opportune to suggest the end of a story, two chapters of 
which are not without some importance. The threads are in a 
correct position, the hooks are there to catch the threads, and 
threads are carried down. One cannot fail to recognise that so 
many accommodating conditions are not accidental. The fungus 
produces spores while attached to the style. From the shape 
and position of these spores it 1s probable that the hyphal 
threads are those of Sporotrichum pulvimforme. More detailed 
information respecting the presence of this fungus on the styles 
of the birch fruit at the time the fruit falls, awaits: further 
investigation that is being carried on. 
Much has been written respecting the relation between the 
higher plant and the fungus that forms the mycorrhiza. 
Frank’s opinion, as expressed in a paper already cited was, 
“that the organic union between root and mycelium, their 
harmonious growth and the close physiological relations which 
must exist, all point to this being a new case of symbiosis. From 
the side of the root we must regard the fungus as a parasite 
which takes from the former food-supplies of the nature of carbon- 
aceous assimilated material ; its minerals, etc., must be taken 
by the fungus itself from the soil, the free hyphe acting as root 
hairs.” 
As regards the birch, it may be pointed out that during the 
first ten years of its life it grows at a rapid rate, lengthening as 
much as 2 to 2.5 feet during the first year. The association with 
the fungus would appear to put no check whatever upon the 
growth of this tree. 
As already stated little was written respecting ectotropic 
mycorrhiza until recently. As a result of research opinions are 
still not agreed. 
Weyland (1912), considers that the fungus in ectotropic my- 
corrhiza is really a parasite and has nothing to do with symbiosis. 
