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As arum europaeum a] id its Mycorhiza. 
Weiss (5) has also described a mycorhiza from the Lower Coal Measures; 
it, however, does not bear so many points of resemblance to that oi Asarum 
as does the one on A my e Ion radicans . 
Significance of the Mycorhiza. It is difficult, if not impossible, 
to assign the exact role played by a mycorhiza in the nutrition of the plant. 
It may be, as stated by Ternetz (6), that some mycorhizas have the power of 
fixing atmospheric nitrogen. Starting from the fact that plants possessing 
mycorhiza are to be commonly met with in soils rich in humus, Stahl (4) 
suggests that the fungus aids the plant in the absorption of the ash con- 
stituents from the soil. He thinks that the numerous Fungi to be found in 
a soil rich in humus are severe competitors with any Phanerogams for the 
available plant food in the soil, and is of opinion that the Phanerogam 
probably benefits in some way by association with a fungus which might 
yield up the ash constituents to it. This might conceivably apply to the 
case of plants possessing an ectotrophic mycorhiza, but certainly is no 
explanation of such a deeply seated mycorhiza as is found in the roots of 
Asarum. Moreover, the soil in which the Asarum europaetim was growing 
was not very rich in humus, nor was it crowded with Fungi. 
Stahl also suggests that the fungus may prepare and transform the raw 
nutritive salts (as absorbed from the soil) into products of assimilation ready 
for the use of the plant, as for example asparagin. He notes the absence 
of any form of calcium oxalate, a substance which is usually associated 
with the assimilation of nutritive salts. As I have stated, calcium oxalate 
crystals are not found in Asarum . This hypothesis seems to fit in with the 
facts so far as they are known. 
According to Gallaud (7) the Fungi of the endotrophic mycorhiza are 
1 saprophytes internes which by means of highly developed haustoria 
borrow some non-living nutritive material from the cells in which they live. 
The plant cells finally kill the haustoria, digest, and partially absorb them. 
The cells, he thinks, defend themselves from the attack of the fungus by 
their digestive power, and consequently the fungus is but little harmful. 
Against this view, in the case of Asarum, is the fact of the fungus being 
confined to the innermost cortical layers and not straying from them. One 
would expect a parasitic fungus to attack the whole of the cortex and the 
soft bast of the stele. Gallaud doubts whether any true mycorhizal fungus 
has been grown isolated from the root of its host plant. 
Relationship between the Plant and the Fungus. The 
question whether the fungus found in the roots of Asarum be a parasite, or 
whether the relationship existing between the plant and the fungus be 
a symbiotic one, is of considerable interest. 
From a purely morphological point of view, the signs of parasitism 
may include destruction or hypertrophy of tissue, hypertrophy of cells or 
nuclei, degeneration of nuclei, unhealthy appearance and poor growth of 
