688 Howard. — On Diplodia cacaoicola , P. Henn.; 
When three days old the mycelium showed signs of darken- 
ing in hue, and this tendency increased till the colour was 
dark olive-green when seven days old. During this colour- 
development oil-drops appeared in the hyphae, the contents 
of which gradually collected into certain portions of the 
mycelium, leaving the rest empty (Fig. 8). 
No further developments were observed in hanging-drops, 
except that the thick-walled hyphae became covered with 
a dark-brown resin-like covering, like that mentioned by 
Bauke in the case of a Diplodia k The old mycelium in the 
cane near mature pycnidia shows this brown covering also. 
In plate-cultivation made with spores from a diseased cane 
by the dilution-method, using the cane-extract medium, pure 
cultures were obtained containing only one colony, which in 
three days developed a copious greyish mycelium, and this, 
in spite of Bacteria, covered the plate and grew into the air, 
forming a dense pile about a quarter of an inch in height. 
When four days old, dark circular hairy bodies were noted, 
which proved to be pycnidia containing the characteristic 
spores of the Fungus when examined on the ninth day. 
When grown in flasks or tubes of the cane-extract food- 
material the development is very similar to that on plates, 
except that when the cultures are free from Bacteria the 
mycelial development is more luxuriant and the surface of 
the food-material becomes covered with a dense felted mass 
of mycelium about half an inch thick, which soon turns black, 
and in which numerous colonies of pycnidia are embedded. 
Such luxuriant development, however, is not so satisfactory 
as that obtained on sterile oak- or cacao-wood infected with 
some of the aerial mycelium from hanging-drops containing 
a single spore. Such cultures, on account of their slow 
development, were found to be of service in maintaining 
a stock of fairly fresh pure-cultures during the progress of 
the investigation, and for use in the infection-experiments. 
Pycnidial formation does not begin in this case before from 
six to ten days, and spores cannot be usually detected in 
1 De Bary, Comparative Morphology and Biology of the Fungi, p. io. 
