( 57 ) 
reaction of cupri-ammonium cyan urate *); with nitrous acid nitrogen 
is produced. 
It was also biologically demonstrated that the thus formed sub¬ 
stance was urea. To this end the crystals were dissolved in broth 
mixed with a quantity of bacteria, then kept for some hours at 
50°. At this temperature there is no growth but the urea is trans¬ 
formed into ammonium carbonate, which in this experiment resulted 
in great abundance. 
Use can also be made of the iris phenomenon *) *) by adding some 
of the substance to yeastwater gelatin and making a plate upon 
which a strong urea bacterium is put. The NEWTON-rings, then occur¬ 
ring, prove that the added material contains urea. 
As the media with uric acid in decomposition, are rendered strongly 
alkaline by the action of the urobacteria on the urea, the successive 
production of two distinct floras of bacteria is observed, one charac¬ 
teristic of the feebly acid or neutral medium, and one proper to the 
alkaline condition of the medium. 
The allantoin produced at the oxidation of uric acid is itself an 
intermediate product, it being subject to further decomposition, which 
is in accordance with the fact that it is much more inconstant than 
uric acid. 
This conversion is analogous to that of the last named substance, 
and so here also is a flora of a neutral and one of an alkaline 
stage; the neutral flora produces an oxidation and an hydrolysis. 
If a hydrolytic agent acts chemically on allantoin, then, after the 
degree of intensity of the hydrolysis, either allanturic acid and urea 
or glyoxilic acid results, whereas two molecules of the latter are 
converted into the more constant glycolic acid and oxalic acid. 
Of these decomposition products, oxalic acid is also easily found in 
the biological hydrolysis. It could be proved that all the four bacteria 
which form part of the “neutral flora” of uric acid, namely B. 
fluorescens liquefaciens, B. fluorescens non-liquefaciens, B. calco- 
aceticum and B. pyocyaneus, produce this substance. This acid 
forms a deposit of calcium oxalate at the scratches of the vessel- 
walls. That the substance was indeed calcium oxalate was confirmed, 
besides by the characteristic forms of the crystals, by its solubility 
in hydrochloric acid, its insolubility in acetic acid and its power of 
decolorising acid permanganate. Moreover, after incineration a mix¬ 
ture of calciumoxid and calcium carbonate remained. 
! ) See footnote 1 on the preceeding page. 
2 ) Beijerinck, Centralbl. f. Bakter. Bd. VII 1901. 
3 ) Sohngen, Kon. Akad. v. Wetensch. 12 Nov. 1908. 
