( 60 ) 
The reaction of Gerard’s liquid was then still neutral, whereas 
the other under these conditions reacted still feebly acid. 
The flora which first appeared proved in both cases to be the 
same and consisted of B. fluorescens liquefaciens, B. fluorescens non- 
liquefaciens and B. calco-acetieum. After repeated transports B. fluor. 
liq. vanished completely, the optimum temperature of this species 
being nearer to 25°, whereas that of the other is about 30°. In the 
neutral liquid of Gerard this microbe could however maintain itself 
longer than in the other. 
The isolation of the bacteria watf done on broth-gelatine. 
On agar-plates, which besides a little phosphate contained some 
uric acid, by which the whole plate was quite opaque, the uric acid 
disappeared around the bacterial colonies under the influence of the 
formed ammonium carbonate. As this compound increased a ring of 
crystals occurred in which calcium urate could be pointed out. If the 
growth took place not at 30° but at 37°, it was found that (from 
garden soil as well as from canal water) the same bacteria as from 
the cultures at 30° were obtained, with the exception of those cases 
when B. pyocyaneus occurred in the material, as this species dispels 
the others more or less completely. 
Uric acid thus proved to be a very good food for this latter microbe 
too, although the power of secreting pyocyanin was lost and could 
only be restored by repeated transplantations in peptone solutions. 
By many experiments it was proved that during the winter of 
1907—1908, as well from canal water as from garden soil at Delft, 
by this method a culture was constantly obtained in which B. pyo¬ 
cyaneus positively predominated. But in 1909 no more a growth 
was to be had containing this species, and when material was used 
rora a garden at the Helder, the results were also negative. 
With a view to get more certainty about this point, I added to a 
rough accumulation with uric acid at 37° a trace of a culture of 
. pyocyaneus. How small soever the number of introduced germs 
roig t be, they were always able to maintain themselves, even in 
e fransports. It seems thus proved that the occurrence of B. pyo¬ 
cyaneus in the soil is but accidental. 
A k° m ° f the alkaline P hase in the decomposition of the uric acid. 
s has been described in the preceding pages B. fluorescens pro¬ 
duces urea from uric acid. If a crude accumulation is allowed to 
s an it may thus be expected that the urea bacteria which, like 
• uorescens, were present in the original inoculation material, will 
™ * * e containing urea the conditions wanted for their 
gr W 18 18 1Iuleed the case as is shown by the intense production 
