8 2 
inacan. Among these, with the exception of No. 29, are the organisms separated 
by Methods 1 and 2, though No. 16 showed such a feeble result in the clam 
medium that it has been disregarded. No. 13, which showed a positive result 
by the third method only, was also rejected. 
CLASSIFICATION 
Nothing had yet been done with a view to eliminating repetition of cultures, 
except the preliminary observation in ‘our media of the fifteen HS formers 
found by Method 2. Of these all had liquefied gelatin rapidly and fermented 
dextrose w.thout the product’on of gas. Variation had been noted in the growth 
upon potato and litmus milk. 
With the aim of separating and determining different forms it was decided 
to grow subcultures of all organisms simultaneously. Transfers were, therefore, 
made from the most recent stab cultures of all blackening organisms to peptone 
water for invigoration. After 24 hours they were thence transferred in duplicate 
to Gelatin stick, sugars, potato, litmus milk, nutrient broth, agar slants and 
nitrate broth. Fresh peptone water cultures were made daily until inoculations 
were completed. Sl'des for m'croscopic examination were also prepared. Growth 
characteristics were noted and comparisons made from day to day, all cultures 
being kept for six weeks. Plate cultures on agar, gelatin, and starch agar were 
also prepared and observed. 
The most recent descriptive chart of the Society of American Bacteriologists 
was used as a guide in choosing media and recording results. 
For the indol test cultures were grown in Dunham’s peptone water for five 
days and the Nitroso-indol-nitrate test made at the end of this period. 
For nitrate reduction, sulphanilic acid and naphthylamine hydrochloride 
were added in equal quantit’es (3 drops of each) to nitrate-broth cultures 48 
hours old. 
Controls were used in both these cases. 
Reduction was unmistakable in all cultures so that it was not necessary to 
repeat the tests after longer periods of growth. 
Six forms were finally separated, repeated tests being made in many cases. 
Potato cultures, for instance, were tried both at room temperature and at 
Side. 
CHARACTERISTICS COMMON TO ALL THE ISOLATED ORGANISMS. 
Preparations stained for flagella revealed the fact that all belonged to the 
genus Pseudomonas, one variety possessing a tuft of polar flagella, the others 
having a single flagellum attached to one pole. Endospores were not observed 
in any of the species. All liquefied gelatin rapidly and digested casein, though 
in one instance the latter process was very slow. All formed hydrogen sulphide 
and reduced nitrates to nitrites. All fermented dextrose, saccharose and glycerin. 
At first they gave strong acid reaction, which began to change about the fourth 
day, the contents of the tube gradually becoming alkaline throughout. In one 
case only, lactose was fermented, though all cultures grew well and produced 
turbidity in lactose broth. The common characteristics here noted will not be 
8 
