24 
Mycorhiza. 
roots of Psilotum , which had been infected with mycorhiza. Here 
the nuclei of the host-cells increased enormously in size and 
contents, while the contents of the hyphae were completely absorbed, 
the chitinous walls, however, remaining behind as an undigested 
clump in the cell. 
In the case of the root-tubercles of Alitus , to which Nobbe and 
Hiltner also ascribed the power of fixing free nitrogen, a proteolytic 
ferment was again demonstrated, though the symbiont is here not a 
true fungus, but like that of the well-known root-tubercles of 
Leguminosae, a bacterium-like organism. 
In Myrica the fungus of the tubercle is confined to a definite 
ring consisting of one to three layers of parenchyma, and there is 
progressive infection of the new tissues formed at the apex of the 
tubercle. The radiating arrangement of the hyphal branches of the 
fungus, together with the club-shaped swellings of their ends, 
point to a relationship with the genus Actinomyces. Here in fact we 
seem to have a case of vegetable “ actinomycosis.” 
Altogether these observations extend our knowledge of the 
relation of host and parasite in a most interesting manner. They 
extend the conclusion already arrived at in the case of Leguminous 
tubercles and of the saprophytic prothalli of Lycopods and Ophiog- 
lossaceae (see Nevv Phytologist, April, 1902, p. 87) of the 
complete mastery of the plant over its symbiont. The relations of 
nutrition are not yet, however, by any means clear. We do not 
know how the plant is enabled to fix free nitrogen. The supply 
of any sort of food to the host from the exterior by the aid of the 
fungus would seem to be difficult, since the external connexions of 
the latter are very slight. 
V. H. B. 
R. Mad^ey, Printer, 151, Whitfield Street, pitzroy Square, 
