A CONTRIBUTION TO THE BIOLOGY OF BACTERIA. 195 
The next step was, therefore, to ascertain if there existed 
a causal connection or simply a concomitance of the pheno- 
mena. For this object the following elementary experiments 
were made. Fresh-filtered urine was put into test tubes, 
their opening closed with cotton and dipped into the water 
bath of 122° F. (40 — 45° C.). After thirty hours the 
reaction was alkaline, ammonia was generated, and countless 
Bacteria found in it. After some time the Bacteria sank to 
the bottom, and the urine was again clear and limpid. In 
spite of the lifeless condition of the organisms ammonia was 
constantly generated, and the degree of alkalescence enhanced. 
In order to determine the latter I made use of a burette, con- 
structed as that for liquor potassse, and added sulphuric-acid 
solution (5 per cent.), drop by drop, to a certain quantity of the 
urine, to which a small quantity of the above-mentioned alco- 
holic solution of rosolic acid was added. The change from a 
beautiful rose-red tint to a bright straw-like yellow, indicated 
that the first drop of acid in excess had been added. Perhaps 
this simple experiment goes far to show that the decomposition 
of urea is not so directly dependent upon living organisms as 
the vitalistic theory implies ; but, on the contrary, that the con- 
tinued action of the temperature of 122° F. (40 — 45° C.) is a 
favorable circumstance, if not an etiological factor of the 
same. Nor can the urea ferment of Musculus be its cause, for 
its action is said by the discoverer to be neutralised in 80° C. 
and by alkalies, both of which are made to act upon the con- 
tents of the retorts in Dr. Bastian’s experiment. It is well 
known that urea is decomposed when its aqueous solution is 
heated in sealed glass tubes, or when in the dry state it is melted 
with an alkali hydrate. Mindful of the latter fact, I charged 
four test tubes with an aqueous solution of urea, and added to 
two of these a small quantity of dilute liquor potassae. Two 
tubes, one with urea and the other with urea and the alkali, 
were sealed in the flame and placed in the incubator at 122° F. 
(40 — 45° C.). The remaining pair was dipped into the water 
bath of the same temperature, and closed with a cotton plug. 
The result was : 
I. Test tube with urea and liquor potassm, cotton plug. 
Generation of ammonia after seventeen hours in water bath. 
II. As I, but without alkali. Feeble generation of ammonia, 
alkaline reaction after 139 hours in water bath. 
HI. Test tube with urea and liq. pot., sealed. Feeble genera- 
tion of ammonia after twelve days in incubator. 
IV. As III, but without alkali, was opened after fifty-seven 
days. Generation of ammonia not distinctly determinable, but 
