1922] RAYNER—NITROGEN FIXATION 231 
with their ericaceous host plants. In ignorance of the work of 
TERNETZ, the conclusion was reached independently that seedling 
roots become infected from the testa subsequent to germination. 
This view proved to be correct, and a pycnidia-bearing fungus was 
eventually isolated with comparative ease from unopened fruits. 
Proof of the identity of this fungus was then provided by reinocu- 
lation into seedlings grown in pure culture and raised from sterilized 
seeds. A remarkable condition of obligate symbiosis was thus put 
on record for Calluna, and the observations made by TERNETZ as to 
the specificity of the fungal strains in the different ericaceous species 
were subsequently confirmed. The characters of the endophyte 
isolated from Calluna agree with those described by TERNETz, and 
the necessary proof is thus provided that the forms experimented 
with by this worker were actually those associated with the five 
plant species concerned. In view of this fact, the suggestion 
previously put forward as to nomenclature (Joc. cit., p. 125) should 
be withdrawn and the name Phoma radiciis Callunae accepted. 
In the paper recording these facts, attention was drawn to 
observations bearing onthe possibility of nitrogen fixation by the 
endophyte. Of these may be mentioned: (1) the vigor and longev- 
ity of seedlings germinated on filter paper moistened with distilled 
water (RAYNER); (2) the wide distribution of the endophyte 
throughout the plant tissues, its development in the intercellular 
spaces of the leaves and emergence to the air from the surface of 
the shoot; (3) the evidence of digestion of mycelium by mesophyll 
cells (see footnote 1). The association of Calluna and other erica- 
ceous species with soils deficient in nitrates in itself provides 
raison d’étre for the remarkable biological relations between plant 
and fungus, assuming fixation of atmospheric nitrogen on the 
part of the latter. 
Experimental observations 
CALLUNA SEEDLINGS IN MEDIA LACKING COMBINED NITROGEN. — 
In experimental cultures, seedlings of Calluna grow readily under 
aseptic conditions in a dilute normal solution made with 1.2 per 
cent agar-agar. In order to test the possibility of cultivation in a 
5 RAYNER, M. C., The ecology of Calluna vulgaris. New Phytol. 12:59-77. 1913. 
