Orchid Mycorrhiza. J. Ramsbottom. 37 
be used. The diversity in the number of species is simply a case 
of the usual “lumping” and “‘splitting.’’ Bernard found in his 
experiments that fungi obtained from different sources, but to 
which he gave the same specific names, varied somewhat in 
their behaviour, and it is quite probable that these physiological 
distinctions are related to slight morphological differences. 
Bernard later recognised certain of Burgeff’s species as falling 
within his, e.g. Orcheomyces Sambucinae, O. mascula, O. insignis 
and O. Luddigi were regarded by him as Rhizoctonia repens— 
but he apparently took into account merely the gross characters 
of growth. 
The endophytic fungus is able to ferment cellulose, which 
accounts for its ability to penetrate cell walls. Burgeff made a 
study of the physiological characters of the species he isolated. 
He found that they were able to absorb carbohydrates in the 
form of sugars, these being in all cases transformed by a diastase- 
invertase in some species, maltase in others. Having regard to 
the prevalent ideas as to the function of mycorrhizal fungi it is 
of particular interest to note that these forms are apparently 
unable to fix free nitrogen: the nitrogen of organic compounds, 
such as peptone, can be made use of as a source of nitrogen: 
ammonium compounds are better assimilated than nitrates. By 
growing cultures in the dark and in an atmosphere devoid of 
carbon-dioxide he established the fact that the carbon com- 
pounds of the soil can suffice as a source of carbon. 
Bernard in his experiments found that the fungi if grown in 
culture gradually became inactive. Cultures two years old were 
quite unable to bring about germination. Burgeff, on the other 
hand, found that his cultures after twenty-six and twenty-eight 
months retained their power. In connection with this point a 
culture of a root fungus which had been regularly cultivated for 
at least eight years, though not used during that time for 
germination, was recently tried. A very feeble germination 
occurred in certain of the tubes. As the activity of the fungus 
when it was first isolated is not known, it is impossible to say 
whether there is any decrease in intensity, though this is pro- 
bable. The gradual attenuation with final loss of activity noted 
by Bernard may be a consequence of ‘‘staling” through too 
infrequent renewal of cultures. He found that the intensity of 
an attenuated form can be increased by extracting it from a 
plant which it had been successful in germinating. 
GERMINATION OF SEEDS—continued. 
The seeds of orchids are very small, the embryo being fre- 
quently only just visible to the naked eye*. They possess a 
* The embryo in Fig. 2 is approximately 200,, i.e. é, ris inch. 
