On two species of Heterosporium particularly Heterosporium echinulatum 
9 
red-brown, and the colonies become dome-shaped. The conidia-bearing hyphae bear 
from 1—3 prolongations of the first head; the mature conidiophores are invisible to 
the unaided eye. 
2. On maltose agar. 
The growth is more abundant than upon glucose both as regards mycelium and 
the number of spores. The sunken mycelium is bright green; fewer vertical, sunk, 
hyphae are formed upon this medium than upon any other. The conidiophores are 
visible to the naked eye. 
3. Upon meat-extract agar. 
The vertical, sunken hyphae are very numerous and long, but are not so deeply 
coloured as they are upon glucose. The surface and aerial mycelia are scanty as 
compared with those upon other media thus making the vertical sunken hyphae easy 
to be seen. The conidiophores are visible to the unaided eye. 
4. Upon plum-juice agar. 
The growth is less rapid than upon glucose or salep-agar; the oil drops contain¬ 
ed in the mycelial cells are more noticeable. In size the colonies become more ex¬ 
tensive than upon any other medium. The mycelial hyphae are bent sharply and are 
not wavy. The sunken mycelium is olive-green in colour, and the conidia-bearing 
hyphae do not produce more than 2 prolongations. No vertical, sunken hyphae are 
produced upon this medium. 
5. On salep agar. 
The surface and aerial mycelia are very scanty, but very numerous vertical, 
sunken hyphae and conidiophores are produced, the latter often bearing as many as 
4 prolongations. 
Heterosporium echinulatum. 
1. On salep agar. 
The general colour of the colony is greyish, very numerous conidiophores with 
as many as 7 prolongations and 14 conidia are produced. 
2. On glucose agar. 
The central portion of the mycelium is grey-green in hanging-drop-cultures, and 
yellowish in petri-dish-cultures of the same age. The mycelium is bent at angles and 
is not wavy, its individual cells are shorter than those produced upon plum-juice agar. 
3. Upon meat-extract agar. 
The conidiophores are not so numerous neither are their prolongations as upon 
other media, at most conidia are produced on one conidiophore. 
4. On plum-juice agar. 
The sunken mycelium is olive-green, and many of the conidia germinate in situ. 
Heterosporium Betae. 
1. Germination of Conidia and development of conidia-bearing 
hyphae. 
The germination of the spores was observed in hanging-drop cultures 
on various media. The spores were obtained from cultures of small pieces 
of mycelium taken from petri-dish cultures, and transferred to hanging 
drops. The mycelia which arose from these cultures produced numerous 
conidiophores after 7 — 8 days of growth. The material for the study of 
the germination of the conidia was obtained from these cultures. The 
spores were taken from the cultures on the end of a blunt platinum 
needle, previously sterilised by heating to redness in a flame, and dis- 
