ago + Transactions British Mycological Society. 
2. Lemperature relations. 
In order to obtain some information regarding the thermal 
relations of this fungus, a number of slope cultures were made 
on malt extract agar and incubated at the temperatures given 
in the following table. The size of the resulting colonies after 
six weeks’ growth are recorded. It appears that the optimum 
temperature for growth is about 15° C., the maximum tempera- 
ture between 25° and 30°C. and the minimum temperature 
between 0° and 1° C. 
Measurement of colonies 
Temperature after 6 weeks’ growth, cm. 
1. Cold storage (0°1° C.) ia | 
2 Incubator (15° C.) 52x 2 
3. Cupboard in laboratory (15° C. in daytime, 4°2 xX 2 
less at night) 
4. 25°C. incubator 3°3x 18 
5. 30° C. incubator nil 
6. 35° C. incubator nil 
3. Production of comdia in pure culture. 
Conidia have been produced in pure culture on sterile apple 
twigs and on malt agar slopes. Those produced on sterile apple 
twigs are formed as in nature. In pure cultures of malt agar 
slopes the process is somewhat different. After four months’ 
growth, dark green irregular roundish bodies were noticed (Pl. X, 
fig. 9). On examination these proved to be little masses of 
stromatic tissue where the hyphae were twisted together to form 
a kind of sclerotium. Sections through these bodies showed 
that they contained large numbers of conidia. Pethybridge(s) 
mentions a similar occurrence in Colletotrichum Tabificum 
(Hallier) Pethybr., a fungus closely related to Myxosporium. In 
Colletotrichum this is the only form of fructification and the 
sclerotia-like bodies are found on dead or dying potato stalks, 
especially on the parts below ground. So far no corresponding 
bodies have been found in nature in connection with Myxo- 
sporium corticolum. 
4. Difference of conidial measurements from those 
occurring in nature. 
A careful study of spore measurement has been made both of 
spores from the apple branch and from those produced in pure 
culture. 
Fresh material was collected in May 1922 from the variety 
James Grieve and 1000 spores measured. They varied in length 
from 25—-45p, the largest number being 36 in length. The 
width varied from 9-18 yp, the majority being 12, in width. 
The spores developed in pure culture were distinctly smaller. 
This observation disagrees with that made by Lewis(z), who, 
