40 
THOMPSON YATES LABORATORIES REPORT 
closely simulating a yeast, others streptococci ; but these forms are not constant, and tend to disappear on 
prolonged subculture. Some forms have a peptonizing action on milk, but others are of so feeble a growth 
that no change takes place. 
In addition to the above we have isolated organisms which we have been unable to classify under 
any of Professor Marshall Ward's groups. We have found it necessary, therefore, to include them under 
a fresh grouping. These are the following : — 
Group A. — Chromogenic micrococci. — These differ from his Group 17 in that they form a marked 
yellow pigment of varj'ing degrees of intensity. They are very common. We have studied 16 forms in all. 
Their liquefactive action on gelatine, like that of Group 19, is not constant, some losing it on prolonged 
subculture, others regaining it. Many of them are feebly-growing forms, especially on potato, and have a 
tendency to become non-chromogenic. A few are capable of peptonizing milk. None of them were 
found to be capable of producing gas in glucose gelatine. 
Group B. — In addition there Is the very characteristic group mentioned above, allied to the 
cladothrix, streptothrlx, saccharomyces, and other fungi, of which we have isolated 5 examples. These 
produce varying coloured pigments — such as dark brown, pink, and white — and a most pungent odour, 
recalling the smell of a damp cellar. I'hey all produce liquefaction of gelatine, and an acid reaction in 
milk, but no gas in glucose gelatine. On potato white chalky growth forms, having the characteristic 
smell, and an appearance like bird excrement. 
Group C. — Lastly, we have isolated a pure yeast form, which produces a pink colour and liquefies 
gelatine, whilst precipitating the casein in milk with an acid reaction. It does not produce gas in glucose 
gelatine. 
