Howard.—On a Disease of Tradescantia . 31 
already stated, and the specific characters were found to 
agree most nearly with those of B. diffusum, Corda, occurring 
in rotten wood, branches, leaves, &C . 1 
It now became necessary to try infection experiments with 
healthy host-plants in order to test the parasitic nature or 
otherwise of the Fungus. 
Preliminary experiments were made by placing a colony 
of the Fungus, with attached food-material, from a pure 
plate-culture, on both the upper and under surfaces of the 
leaves of apparently healthy host-plants growing in the 
greenhouses, and also out of doors. No infection took place, 
the leaves being kept under observation for fourteen days. 
Next, a large quantity of infected Tradescantia material 
was collected, ground up with sand, and the extract filtered 
through a Pasteur filter. The filtered extract was then 
collected in minute capillary tubes, sterilized when drawn, 
the fine sealed ends of which were then broken as they were 
pushed into the tissues of the plants. Healthy plants infected 
with this extract did not show any ill effects, although as 
many as six capillary tubes were placed in each. 
Afterwards infection experiments were made on a large 
scale, using healthy leaves to which a portion of the internode 
was attached, floating on water. Growing hyphae, germi¬ 
nating spores, or spores direct from the conidiophores, were 
sown on the upper and under surfaces of the leaves of both 
species of host-plants, the epidermis being left in the normal 
condition in some, or pricked with a sterilized needle in 
others. A similar set of experiments was made, in which 
a drop of food material was used in addition 2 , and in all 
cases blank experiments were performed to serve as a control. 
Only in rare instances did infection take place, and in all 
such cases the entering hyphae were found to be olive-brown 
coloured and of a different character from the normal mycelium 
of the Botryosporium. On the whole, the infection experi¬ 
ments demonstrated the non-parasitic nature of the Fungus 
1 See Massee, Brit. Fung. FI., Vol. iii, p. 291. 
2 See Marshall Ward, A Lily Disease, Ann. Bot., Vol. ii, p. 355. 
