On the Morphology and Development of Phoma Richardiae n. sp. 
245 
with these, in one instance, Phoma -like pycnidia occured. In pure cultures 
the last-named developed secondary fruit forms; and as it seemed possible 
that this fungus was of a parasitic nature, an investigation into the mor¬ 
phology and physiology of the species was undertaken. The work was 
suggested by Prof. Dr. H. Klebahn, and has been conducted under his 
supervision in the Botanische Staatsinstitute, Haml>ur g. 
I should like at the outset to express my thanks to the Director of 
the Institute for the use of the Laboratory and materials, to Prof. Dr. 
Brick, Station für Pflanzenschutz, Hamburg, for assistance in 
connection with the literature, and especially to Prof. Klebahn for the 
constant advice and assistance he has so kindly afforded me throughout. 
The fungus was first cultivated on plum-juice agar 1 ); pycnidia, ex¬ 
truding single-celled hyaline spores were quickly formed; later on chains 
of brown, pear-shaped conidia were developed on the mycelium and 
around the masses of extruded pycnospores, while gemma-like structures 
appeared in the agar. 
Subsequently moist-chamber, PETRi-dish, and tube cultures were 
made on a variety of media, minor differences being observable in the 
various cultures. 
The drawings have all been made by the aid of the camera lucida. 
1. The mycelium. 
The best growth has been obtained on plum-juice agar. It will be 
convenient therefore, to describe first the appearance of the mycelium on 
this medium. In a moist-chamber culture a central mass of intertwined 
hyphae arises around the point of inoculation, from which main branches 
radiate, giving off smaller branches in all directions (Fig. 1, /). Side 
walls 12—25 ja apart are laid down 0,3—0,4 mm behind the growing point. 
Commonly a hypha forks two or three times in front of the first cross 
wall; but branches also arise further back. The pycnidia tend to form 
more or less in a circle in the central mass of mycelium, and in lines 
along the main branches. The young mycelium is at first colourless or 
very pale green, and contains numerous spherical oil-drops. The branches 
are slightly constricted at their points of origin. Fusions of hyphae occur 
frequently, especially towards the edge of the agar drop (Fig. 1, 2 , j). 
As age increases many of the cells become barrel-shaped or distorted, 
assume a yellowish colour and their oil drops often run together (Fig. 1, 4)\ 
the agar also assumes a darker colour. As the mycelium dies its proto¬ 
plasm becomes concentrated in short stretches, the cells of which are 
usually irregular (Fig. 1, j, 6). 
PETRi-dish cultures show marked concentric rings, due to the for¬ 
mation of numerous and scanty pycnidia respectively in alternate rings of 
1) Plum agar. Half a dozen dried plums were boiled with 500 ecm water 
for 2 hours. The solid matter was then filtered off and 20 g agar, previously purified 
by Macé’s method (Traité pratique de Bactériologie, Paris 1889) were added. The 
mixture was boiled for half an hour, and then filtered in steam till the filtrate came 
through clear — a process extending over about a day and a half. The filtrate was 
made up to 1000 ccm, filled into SoxHLET-bottles, and again sterilized. For moist 
chamber cultures it was found convenient to dilute with an equal volume of water. 
The medium is slightly acid. 
