On two species of Heterosporium particularly Heterosporium echinulatum g 7 
April 1912 these lower leaves were inoculated with spores taken from 
two damp-chamber cultures of salep agar and dispersed in tap-water. 
Owing to the fact that the Heterosporium sp. formed very poor growths 
at this time on culture media, only a comparatively small number of 
spores were attainable for inoculation purposes. The plants were kept 
under bell-jars. One pot was taken in which the plants were growing 
in sand, the other pot contained healthy plants growing in earth. 
On May l stf 1912 these plants were examined, but no Heterosporium 
was found. These experiments seemed to show that Heterosporium sp. and 
Hormodendron sp. behaved as saprophytes, and Alternaria sp., perhaps, 
as a weak parasite. 
2. Infection experiments on Dianthus Caryophyllus with JET. 
echinulatum, 
■ ' ■ ’ .A, ■ ' * f 
Experiment V. 
On 19 th December 1911 two small plants of Dianthus („Queen 
Louise“) in separate pots, and under separate bell-jars were inoculated 
with spores of Heterosporium echinulatum taken from a pure culture on 
salep agar. The spores were dispersed in tap water, and were applied to 
the upper surface of certain leaves by means of a small paint brush. On 
the lower leaves of these plants the upper surface was easily wetted when 
touched by the brush charged with the water containing the spores; but 
it was found impossible to leave drops of water upon any of the young 
upper leaves unless the upper surface had previously been rubbed over. 
In this experiment, however only the lower wettable leaves were inoculated. 
The leaves so treated were marked with little loops of copper wire so 
placed that they indicated the place where the brush had been. Six leaves 
on one plant, and seven on the other were inoculated in this manner. 
On December 20 th 1911 the inoculated areas of two leaves were cut 
out and killed in acetic alcohol; this process was repeated upon the 21 st , 
22 nd and 23 rd December. The four lots of two pieces each were washed 
in alcohol, and finally imbedded in paraffin in the usual way with a view 
to subsequent microscopial examination of the germination and development 
of the germ tubes, and the penetration of the host tissues. 
On January 3 rd the plants were examined; they had been kept under 
bell jars the whole time in order to imitate as far as possible the con¬ 
ditions under which the carnations are grown during the winter months 
in the nurseries. Both plants were found to be covered in places with 
moulds of various kinds, notably a species of Botrytis. One plant was so 
rotted that upon being touched it fell into two pieces close to the earth. 
No trace of H. echinulatum was observed. One leaf which had been 
inoculated was cut off from the more healthy of the two plants, and placed 
in a test tube with a little water in the bottom in order that the enclosed 
atmosphere might be kept moist; the tube was finally corked up. On 
January 15 th this leaf showed a typical disease spot with two concentric 
rings of conidiophores upon the inoculated area. It was observed that 
the greatest amount of aerial hyphae was upon the lower side of the leaf. 
Microscopical examination showed that this spot was indeed due to 
H. echinulatum, spores and aerial hyphae being present in great quantity 
