Mould Growths upon Cold-store Meat. 115 
others that have not yet shown growth at — 6° C. will be found 
capable of development between — 6° and o°C.; this will 
shortly be tested. Monvoisin(13) states that mould spores (species 
not stated) will not germinate under cold-storage conditions, 
but that these forms, if allowed to germinate for sixteen hours 
at ordinary temperature, will continue their growth in the cold- 
store and produce new sporing bodies in the course of four to 
five months. Monvoisin does not state definitely the forms with 
which he experimented, but he implies that they were the 
species mentioned above. Our own results show that the spores 
of Cladosporium herbarum germinate even at — 6°C., but that 
subsequent growth is more rapid if germination has taken place 
for a short period at ordinary temperature. Failure to get some 
of the other species to develop at — 6° C. may perhaps be due 
to the conditions of humidity being different from those in 
Monvoisin’s experiments. There is no doubt that some of these 
mould contaminations are due to the meat being exposed to tem- 
peratures’ above 0° C., especially a few degrees higher than this, 
as at more enhanced temperatures bacterial growth is so vigorous 
that mould development is inhibited to a great extent. On the 
other hand, it has been shown that prolonged storage may 
induce the formation of certain of these mould growths, e.g. 
“Black Spot,” even at several degrees below o° C. Shorter 
storage at a temperature just below 0° C. will also give oppor- 
tunity for the development of some of these moulds. 
The spores of all mould fungi found on cold-store meat retain 
their vitality for long periods, several, notably Cladosporium 
herbarum, Penicillium expansum and Thammnidium spp., re- 
maining alive after being subjected to a temperature of — 6° C. 
for two years. A period of three years at this temperature has, 
however, killed even these forms unless growth has already 
occurred in the cold store. 
Other common mould fungi also retain their vitality for long 
periods at low temperatures. For instance, spores of Botrytis 
cinerea, Aspergillus niger and Acrostalagmus cinnabarinus, ger- 
minated after being kept for a year on the surface of culture 
‘media at — 6° C., but spores of Cephalothecium roseum, Fusarium 
coeruleum and Rhizopus nigricans were killed under these con- 
ditions. It is noteworthy that prolonged exposure to cold retards 
the rate of germination of mould spores, and that young mycelia 
are more quickly killed by low temperatures than are spores. 
Recent research has indicated that even thin-walled fungal 
spores retain their vitality for much longer periods than was 
formerly supposed, and the present results confirm this. 
In the course of this work it has been necessary to undertake 
‘a systematic study of many strains of certain of these fungi 
8—2 
