I 2 I 
A Inus and Elaeagnus . 
withdrawn from the organisms by absolute ethyl alcohol, but was retained 
by them when amyl alcohol was used as a dehydrating agent ; which 
reactions clearly indicated that they were Pseudomonas radicicola , according 
to the investigations of Harrison and Barlow. 
Exactly the same results were obtained when maltose or glucose 
replaced saccharose in the above culture medium. Solid media were also 
prepared by adding 2 per cent, agar-agar to the above media, boiling, and then 
pouring into sterile Petri dishes and allowing to cool. These media were 
inoculated with very dilute crushed nodular tissue, prepared as above, 
by means of a sterile platinum loop, and incubated at 25 0 C. Very charac- 
teristic colonies were produced on the agar media, which were ovoid 
to circular in shape, with an entire margin, slightly raised above the surface, 
translucent, shining, and mucilaginous. They increased in size from 0*5 mm. 
diameter in one day to 1*5 mm. diameter in three days. 
Streak and stab methods of cultivation produced equally typical 
growths. The streak produced an abundant, translucent, shining, mucila- 
ginous growth, along the line of infection, with an entire margin, increasing 
in opacity, size, and viscosity from day to day. The stab induced the 
formation of a large typical colony on the surface of the agar, and a filiform 
growth along the stab in the medium. 
The colonies embedded in the agar medium were very small, translu- 
cent, and disc-shaped or lenticular. 
All the above cultures, after a period of incubation lasting four days 
or upwards, revealed on microscopic examination the presence of some 
larger organisms, tending to become ovoid in shape, amongst the cha- 
racteristic rod-shaped Pseudomonas radicicola (Fig. 10). These larger 
organisms also contain the densely stained round bodies which were present 
in the rods, their larger size being caused by an increase in the envelop- 
ing capsule. Division takes place so that one organism contains only 
one of the small bodies, which then grows until it fills the surrounding 
capsule, and the whole structure becomes spherical in shape and appears 
to have a very definite cell-wall (Fig. 11). 
When the larger bodies are present in the colonies on the solid 
media, a white opaque appearance is assumed. The agar media were 
very favourable to the production of the larger spherical form, whilst in 
liquid cultures their appearance seems to be correlated with depletion of 
the medium of its carbohydrate, their source of energy, and probably also 
with the accumulation of the products of their own metabolic activities. 
That they are better able to resist the influence of the external environment 
than are the actively motile bacilli was demonstrated by boiling two 
cultures for ten minutes, one of which contained only the small rods, whilst 
the other contained only the larger spherical bodies, and subsequently 
inoculating freshly prepared culture media with them, and incubating 
