A CONTRIBUTION TO THE BIOLOGY OF BACTERIA. 197 
that the solution was too strongly acid^ and the generation of 
ammonia too slow in order to change the reaction, In the next 
series a much weaker solution was employed. Eetorts charged 
with the same, and prepared in the manner of Mr. Bastian’s urine 
retort, i. e, with and without liq. pot., in proportion to the degree 
of acidity. Here, also, the result was similar to that in the case 
of the urine experiment. After ten to fourteen days the solu- 
tions mixed with liq. pot., and after fifty- seven days those with 
unbroken tubes all contained innumerable organisms. 
As regards the forms of Bacteria which I found in all the 
above-described series of experiments, the greatest number were 
micrococci (Billroth), both in their characteristic movements as 
separate individuals, or linked in varying numbers and at rest, 
singly or in zoogloea colonies. The rods and bacilli were not so 
numerous ; their contents appeared to be granular. In several 
specimens I also found forms much resembling ascococcus (Bill- 
roth). Here also I met with the zoogloea-like masses already men- 
tioned, but am unable to determine whether or not they were 
organisms, as they showed no kind of movement, nor could I 
observe any multiplication of their elements. 
It still remains to be proven that the multiplication of 
organisms in these fluids, treated by high temperature, and in a 
minimum of free and absorbed oxygen, is causally connected with 
the decomposition of urea and the generation of ammonia, which 
here seems to be the source for nitrogen. 
The change in the following series of retorts, kept in the in- 
cubator during forty -one days, will conclusively demonstrate that 
ammonia takes such a role : 
I. In dilute MayeHs solution and urea (3’0 grms., 200 c. c.). 
The fluid remained clear, reaction alkaline, contained micrococci, 
spheroids, rods, and bacilli. 
II. In dilute Mayer's solution and urea, with forty drops 
liq. pot. (5*85 per cent.) ; little sedimentation, fluid clear, 
reaction alkaline, few moving micrococci and spheroids, together 
with crystals and amorphous, granular masses. It appears 
here as if the process of multiplication had already passed over. 
III. In dilute Mayer's solution with dilute solution of caustic 
ammonia, which was introduced in the manner as the liq. pot. 
tubes in the first series, and then broken. Strong and diffuse 
turbidity, reaction alkaline, immovable organisms (micrococci, 
spheroidal forms, rods, and bacilli). 
IV. In dilute Mayer's solution and urea, and a tube containing 
fifty drops of sulphuric acid (5 per cent.), which was introduced 
and broken as above. Fluid clear, low degree of acidity, here 
and there a micrococcus. 
Finally, a portion of the contents of retort IV was divided and 
