January, 1918.] THE ORCHID REVIEW. gS 
was shown experimentally by sowing seeds of Phalenopsis and infecting 
some cultures with their own endophyte and others with fungi obtained 
from the roots of Cattleya and Odontoglossum. Thus, using the endophyte 
from Cattleya, the seed was killed, no germination took place, and there 
was no digestion of the fungus by the cells of the embryo, With that from 
Odontoglossum, infection of the seed occurred, germination was at first 
normal, but was followed by the digestion of the fungus in the cells of the 
embryo and subsequent arrest of growth. Infected by the fungus found 
in the parent plant, germination proceeded in the usual way and gave a 
well-developed seedling. Again, a high degree of physiological adaptation 
was shown by experimental cultures which indicated a critical stage in the 
development of the seedling —earlier or later according to the species. In 
some Orchids practically no germination takes place without infection ; 
in others, presumably relatively primitive, ¢.g., Bletilla hyacinthina, 
development goes as far as the production of a tubercule with several 
leaves; it never reached the stage of root-formation in any species 
investigated by Bernard. Of great biological interest also is the experi- 
mental demonstration that the Orchid plant sets a limit to the spread of its 
fungus partner, shown not only by digestion of the mycelium in certain 
cells of the root, but also by complete exclusion of hyphe from the 
chlorophyllous tissues of the shoot. 
In 1909, Dr. Hans Burgeff published a monograph on the root fungi of 
Orchids, in which he reviewed and confirmed the work of Bernard. He 
also gave an account of his own researches. on the mycorhizal fungi of 
many Orchid species, which he referred to a new genus, called Orcheomyces, 
without making any definite suggestion as to its systematic affinities. 
Bernard had referred these endophytic fungi to the genus Oospora when 
first isolated, but afterwards transferred them to Rhizoctonia. Both 
Bernard and Burgeff found that these root-fungi could be grown on artificial 
media. The latter cultivated one species for over two years without its 
vitality being impaired, and he expressed the opinion that in some cases the 
fungi isolated from native Orchids can be used for inducing the germination 
of tropical species. The series of experiments suggest that the degree of 
dependence varies in different Orchids. The more specialised the relation 
between the two partners, the more easily is the adjustment thrown out of 
gear by cultivating the fungus outside the plant. 
When growing as endophytes, spores are not formed, hence the 
systematic position of the fungi remains doubtful, a point which gives a 
special interest to the case. of the curious saprophytic Orchid, Gastrodia 
elata, as described by Kusano, in 1911 (Journ. of Agric., Tokio, vol. 
No. 1). Gastrodia elata is a native of Japan, where it is frequently iad 
growing in oak woods. It had been assumed to be a humus saprophyte 
