8 9 
the Mycorrhiza of the Maratliaceae. 
On the other hand, it is probable that the pressure of the cell-walls of 
the host upon the developing spores is responsible for the unusual shape of 
some of the mature spores (Text-fig. 7, vii). 
iv. The probable life-history of the endophyte. 
In no case, even in very old decaying roots, has a resting spore been 
observed to germinate in situ ; it therefore seems probable that germination 
never takes place until, on the complete decay of the host-root, the spore is 
eventually deposited in the soil. 
Dastur ( 1 . c., p. 199) states, with reference to Phytophthora parasitica , 
that the ‘ resting ’ conidia, if kept moist, retain their vitality for over nine 
months, when they germinate by one or more germ-tubes, but do not 
necessarily require a period of rest. 
It is not unlikely that a similar statement holds good for the resting 
spores of our fungus ; these spores when finally set free in the soil, where 
they would be preserved under moist conditions, probably germinate direct 
after a varying period of rest, giving rise to one or more germ-hyphae, 
which, either at once or after a while, meet with a suitable host-root, the 
epidermis of which they penetrate in the manner described above. 
The thickness of the wall and the absence of a definite papilla indicate 
that the resting spores are not sporangia, but specialized conidial growths. 
It is possible that the suppression of vegetative vigour and of sporangia 
formation on the part of the fungus, due to lack of oxygen or to some other 
cause (or causes) at present unknown, are determining factors in their 
production. 
According to Magnus ( 32 , p. 216) certain portions of thick- walled 
hyphae of the endophyte of Neottia Nidus-avis persist throughout the 
winter after the decay of the host-root and germinate (‘ zu neuem Leben zu 
erwachen ’) in the following spring and thus infect fresh host-plants. He 
refers to these structures as • sclerotia ’ or ‘ cysts \ This fact is interesting, 
inasmuch as it points to the possible evolution of highly specialized resting 
spores by the local modification of ordinary vegetative hyphae for a repro- 
ductive function. On the other hand, the complex nature of the wall and 
the striking resemblance which the spores under discussion bear to oospores, 
especially during the later stages in their development, suggests their origin 
from parthenogenetic oogonia ( = parthenospores), with complete suppression 
of the male organs. . 
2. Cultural Experiments. 
Many attempts to grow this fungus on various artificial media, both in 
Petri-dishes and in hanging-drops, met with no success. No growth of the 
fungus resulted when pieces of root of Marattia or of Angiopteris , the 
surface of which had previously been sterilized , were placed in or upon 
various artificial media (cf. Rayner, 1 . c., p. 119). The surface of the root 
