142 
W. J. Dowson, 
of water containing spores upon the upper surface of the very youngest 
of leaves, so that in the case of young cuttings rain may account for 
the mode of inoculation. During the winter months both the young plants 
for next year and those of the same year’s growth are kept under glass 
During wet and damp weather these plants will be found upon exami¬ 
nation to be covered with a number of moulds besides H. echinulatum 
chief of which is Botrytis sp. 
The longevity of the spores produced under natural conditions was 
not exactly determined, but they can apparently germinate after some 
weeks to judge from the fact that material with large spots brought from 
the nurseries into the laboratory and kept for a fortnight, gave a sus¬ 
pension of spores in water, all of which germinated; some of these spores 
must have been at least a month or five weeks old. In infection experi¬ 
ment VI, the spores used for inoculation were obtained from a clean- 
culture 6 weeks old and proved capable of infection. Infection from 
the ground is perhaps also possible: spores fallen on to the ground 
from diseased plants, afterwards removed, may be splashed by rain 
upon the leaves of freshly planted carnations. Infected leaves collected in 
the autumn and winter months were kept in the open during the winter; 
and some of these placed in guaze bags were hung from a horizontal 
pole, so that they swung a little way off the ground. Others were placed 
in pots with a wire netting above them to prevent them from being 
blown away. These wintered leaves were examined in the middle of 
April, but no trace of spores of H. echinulatum was found. Perithecia- 
like bodies were present which upon examination proved to be filled with 
an oil-like substance, and might have been perithecia or pycnidia in a 
young stage. Upon soaking in water over night, the old disease spots 
could be recognized as black decayed patches. Some of these were cut 
out and placed in petri-dishes on plum-juice agar; no H. echmulatum 
ever made its appearance in these cultures; on the other hand sapro¬ 
phytic moulds were plentiful. 
The material bearing the Perithecia-like bodies was not further ob¬ 
served and the question as to whether they might possibly be the ascus 
stage of H. echinulatum was not entered into. 
VI. Conclusion. 
1. A new species of Heterosporium has been found upon the lower 
leaves of Beta vulgaris and has on this account been given the name 
of H. Betae. 
The infection experiments showed that the forms described as Hetero¬ 
sporium Betae and Hormodendron- sp. are saprophytes or perhaps very 
weak parasites, wounded and dying tissue only being invaded by the 
mycelium of the Heterosporium. The parasitic nature of Heterosporium 
echinulatum was again conformed. 
2. The mycelium of H echinulatum in the tissues of Dianthus is 
intercellular and without penetrating haustoria. Infection takes place in 
from 6 — 7 days after inoculation, either by hyphae piercing the epidermis, 
probably the middle lamella between two epidermis cells, or by way of 
the stomata. Conidia are again produced by the parasite after a period 
of from 3—4 weeks growth within the Dianthus tissues. The hyphae 
