2 BOTANICAL GAZETTE [JANUARY - 
of fungi and algae, and the embryos may be killed because of being 
covered by these organisms, or more likely by injurious substances 
produced by the decomposition of these organisms. The work of 
BurGEFF (4) and BERNARD (2) demonstrates that death may be 
due to pathogenic fungi, and the writer’s experiments in trans- 
planting seedlings from tubes to open pots demonstrate clearly 
this danger. In addition to these factors, attention must be given 
to preventing loss due to insect pests. As suggested, however, there 
are apparently inherent characteristics of the seeds which make 
for refractory germination. It is this which attracted the attention 
of BERNARD, who in a number of publications presented evidence 
tending to show that the germination of the seeds and the sub- 
sequent growth of the seedlings are dependent upon infection by 
certain strains of the fungus which generally is found living in the 
orchid root, and which BERNARD considered to be Rhizoctonia. 
BURGEFF came to substantially the same conclusions, maintaining 
that germination was possible only when the embryo became 
infected with the proper strain of the fungus, to which he gave the 
name Orcheomyces, without attempting to classify it. 
BERNARD and BurGeErr both pointed out that infection of the 
embryo began at the suspensor end of the seed, and that in the 
case of Cattleya and related forms the primary infection occurred 
through the delicate suspensor. Growth occurred if only the 
lower portion of the embryo became infected, and if the infection 
continued beyond approximately the lower third of the embryo, 
then death of the embryo resulted. It was also observed in germi- 
nating embryos that the fungus disintegrated in the infected zone, 
forming clumps of disintegrated hyphal material in the cells similar 
to the clumps found in cells of the root. It was the opinion of 
BERNARD that the fungus was digested by the orchid embryo. The 
essential point to be noted, however, is that a delicate balance 
between the host and the fungus apparently must be maintained in 
order to insure germination and also to prevent death of the embryo. 
Granting for the present that a symbiotic relationship exists 
between the fungus and the embryo, it is nevertheless true that 
failure of germination is more common than success, even when 
the fungus is provided. BErRNARD’s experiments reveal case after 
