Mould Growths upon Cold-store Meat. 121 
II. MAcROSCOPIC CHARACTERS OF STRAINS. 
Although the various isolations approach each other so as to 
be almost indistinguishable under the microscope, to the naked 
eye there are considerable differences between them as indicated 
in the table, p. 125. Few cultures of the fungus isolated during 
the present work were absolutely identical in appearance. The 
strains were grown on Dox’s medium with the full amount of 
sugar (30 gms. per litre). This medium proved to be the best for 
differentiating between the various strains, the cultures being 
compared at the end of two months’ growth. Growth on this 
medium was luxuriant, and two characters were used to differ- 
entiate the strains: 
(x) Colour. 
(2) Texture of colony—whether “woolly” or not. 
The “woolly” texture of some strains is due to the aerial growth 
of sterile mycelium—the hyphae being often very fine and 
almost hyaline—forming a layer over the conidiophores. The 
characters of the various strains were much the same when 
grown upon steamed potato. 
III. PHysIoLOGICAL CHARACTERS OF STRAINS. 
1. Influence of Temperature. 
The approximate range of temperature within which each 
strain would grow was determined. The different strains show 
considerable divergence in this respect, and the grouping of the 
strains, according to this character, does not follow the arrange- 
ment according to other characters; the table given below is an 
attempt to classify them according to both. 
As already recorded, some strains proved capable of growth 
below freezing point, at — 6°C., and probably others which 
would not grow at this temperature could develop at a slightly 
higher temperature, as all the strains isolated from “Black 
Spot”’ on meat in cold storage grew well at 2° C. Temporary 
freezing up to a month at — 6° C. had no effect on the rate or 
percentage of germination of the spores subsequently tested at 
room temperature, but prolonged freezing at — 6° C. eventually 
killed the spores of most strains, except such as proved capable 
of germination and growth at this temperature. 
Temporary freezing (up to three weeks) of the vegetative 
mycelium of strain S had no permanently adverse effect, beyond 
greatly retarding growth. 
2. Influence of Light. 
With a view to the possibility of distinguishing forms of 
Cladosporium from those of Hormodendron, according to the 
