83 
Nectria galLigena , Bres. 
Other media containing starch or derivatives of starch were tried with 
and without glycerine, such as acid pea-agar and acid haricot bean-agar 
(o-t per cent. N. HC 1 ), prune juice, oatmeal-agar, &c., with the same 
result. 
The agar-glvcerine media were the first to be tried, but these- cultures 
had to be fixed and cut before the asci had developed, on account of the 
drying out of the medium, and the central cells of the perithecium, which 
will be more fully described later, showed all the characteristics of normal 
young perithecia on bark. After these initial trials the potato + i per cent, 
glycerine medium was used throughout the rest of the investigation, as it 
was found to give the most satisfactory results. Ascospores from freshly 
gathered dehiscing perithecia on bark in the spring of 1918 completed two 
life-cycles from ascospore to ascospore during the summer months on the 
potato-glycerine medium. 
The potato slopes were prepared as follows : A wad of absorbent 
cotton-wool was placed at the bottom of the test-tube and the potato on 
the wad. A sufficient quantity of 1 per cent, glycerine solution in distilled 
water was poured into the tube so as to completely cover the whole of the 
potato, then the tubes were autoclaved and stored until required. Before 
inoculation the superfluous glycerine solution was poured off. In this way 
there remained sufficient moisture to last throughout the period of develop- 
ment, if taken out of the incubator after the first two or three days. What 
effect the glycerine has on the development ‘of the fungus is not known. 
After inoculation, the culture tubes were placed in the incubator and 
kept at a temperature of 25 0 C. for the first few days, and then left on 
a shelf in the laboratory, where they were exposed to direct sunlight until 
11-12 o’clock in the day during the summer months, in order to give 
them, as far as sunlight was concerned, approximately the same conditions 
as the tree from which the fungus had been obtained. This treatment 
proved highly satisfactory. It was then thought that perhaps a little 
mechanical pressure might hasten the development of perithecia, as, in the 
host plant, the mycelium of the fungus is very densely coiled and develops 
in considerable quantity before the bark is ruptured. Some of the cultures 
were pressed against the sides of the test-tubes with a sterile glass rod. 
The fungus, however, developed so well without the pressure, and the 
different cultures varied as to the amount of mycelial development, probably 
owing to the small differences in moisture content, size, and other properties 
of the potato slopes, that it was not possible to come to any definite 
conclusion on this point without further work under much more stringent 
standard conditions. During the process of elaborating a suitable medium, 
the possibility of a symbiotic relationship between a bacterium and N.galli- 
gena had to be considered, more especially as the microtome preparations 
of Nectria growing on bark frequently showed the presence of a rod-shaped 
