58 Transactions British Mycological Society. 
turned and the “host”’ has become the aggressor, even attracting 
the fungus to the embryo. We are short of definite facts—there 
is a conflicting mass of detail on such an important point as the 
relation between the endophyte and the soil—and until these 
are obtained one theory seems as good as another. 
It would be indeed strange if the difference between ecto- 
trophic and endotrophic mycorrhiza should resolve itself into 
a case of the fungus being parasitic on the flowering plant in 
the former, while in the latter the flowering plant is parasitic 
on the fungus. 
I am indebted to Mr E. H. Ellis for the photomicrographs, 
with the exception of Figs. 1 and 4, for which I must thank 
Mr R. Jf. Tabor. 
While the above was in the press an important paper by 
H. Christoph entitled ‘‘ Untersuchungen iiber die mykotrophen 
Verhaltnisse der ‘Ericales’ und die Keimung von Pirolaceen”’ 
appeared in Beih. Bot. Centralbl. XxxvVIII, pp. 115-157 (1921). 
In it the author controverts the results obtained by Rayner 
concerning the necessity of the root-fungus for seed-germina- 
tion (cf. p. 48). It should be noted, however, that he has not 
seen the full description of Dr Rayner’s researches, but appa- 
rently only an abstract of her preliminary account. Christoph 
concerned himself with the manner in which the fungus reaches 
the roots of the Ericaceae, whether from the soil or from the 
seed coat. His first series of experiments were performed with 
cuttings. He took both large and small green side shoots from 
plants of Calluna vulgaris both wild and cultivated. These were 
planted in shallow pots in humus heath soil—the soil in the one 
pot being sterilized and that in the other not. In both experi- 
ments a number of cuttings struck and succeeded in establishing 
themselves. The roots of the cuttings in unsterilized soil became 
slightly infected, but no fungus could be found in those growing 
in sterilized soil. On replanting and transferring the latter 
cuttings to sandy soil they still remained free from fungal in- 
fection and continued in that condition for two and a half years. 
Similar experiments with cuttings of Evica carnea gave 
analogous results. Both series succeeded and those planted in 
sterile black heath soil, and after one and a half years trans- 
ferred, remained free from fungus infection for two and a half 
ears. 
The plants without fungi in their roots were in just as good 
a condition as those which became infected and Christoph is of 
the opinion that the fungus is of no assistance to the plants and 
must be regarded as a harmless parasite. 
A second part of the paper deals with germination experi- 
