65 
the cell behind the conidium being slightly bulbous or swollen. 
These conidia were found to germinate slowly in from six to 
nine days in hanging-drops of distilled water, and to give rise to 
secondary thin-walled conidia which germinated readily and 
produced further thin-walled conidia which in turn pushed forth 
delicate hyaline germ-tubes. The secondary conidia may them- 
selves become dark in colour, and form, along with the original 
conidia, a Coniothecium stage of the Phoma. This Coniothecium 
form has been found on coffee twigs, but never, to date, in the 
tissues. No further stage in its development has been observed. 
Pycnidial formation takes place after the lapse of six weeks.: 
‘The conidia or pycnospores are continuous, hyaline, though red- 
yellow in the mass, elongated, up to 5 uw by 1 win breadth, and 
guttulate. The coniodiophores are half the length of the conidia. 
yenospores in nature measure 4-5 w by 1-5-2 yp, are elongate- 
ovate, the longer spores being the narrower in proportion and 
are contained in pycnidia which are 2-5 mm. in difmeter, black 
and carbonaceous. In cultures, the pycnidia are smaller, the 
largest measuring. up to 2 mm. in diameter. oO ascigerous 
stage has been found in any of the cultures though they have 
been kept for over eight months. Chlamydospores appear 
‘before pycnidial formation takes place. They are formed by — 
breaking up of the mycelium, and, while at first irregular in shape 
and more or less hyaline, they eventually become globular, 
thick-walled and brown. They measure up to 20 yp in diameter. 
They germinate in drops of rain-water in from fourteen to 
twenty days. In an old culture, chlamydospores become so 
numerous that they can be seen by the naked eye as dots in the 
course of the mycelium. 
On sterilised coffee-wood blocks, Phoma grows rapidly. © 
‘Pycnidia are produced in abundance in twelve days. They 
measure up to 2 mm. in diameter, and their spores up to 5y & 2p. 
The Coniothecium is also produced in plenty. Microscopic exami- 
nation of the blocks showed the mycelium of the Phoma pene- 
trating medullary-ray elements and pitted tracheids to a depth 
of 3 mm. in twelve days. 
Inoculations with Phoma sp.: the part played by the 
Variegated Bug.—Inoculation experiments similar in all respects 
to those performed with Colletotrichum on coffee were carried out 
with material from the Phoma cultures. Pyecnospores or chlamy- 
dospores and mycelium were placed on upper and under surfaces 
of leaves, on stems at nodes and along internodes, and in nodal 
and internodal wounds of stems. The total number of inocu- 
lations was sixty, and of these only one was successful. In it 
pycnospores had been placed on the unbroken internodal bark of 
a branch, the apical leaves of which began to droop after two 
months. Mycelium was found in the branch tissues near the 
point of inoculation, and Phoma was subsequently recovered. 
It is difficult to explain why all the Phoma inoculations 
except one were negative, and to reconcile the apparent difficulty 
2 13917 B 
