( 521 ) 
ammoniumsalt that has become free contribute to the rapid rise of 
the alkalinity of the culture-liquid. 
Provisional experiments proved that with a ureum-quantity of 
+ 5 °/, in these cultures the best results could be obtained ; with 
this ureum concentration growth is still very good. 
In a way guite analogical with the ammoniumsalts behave diffe- 
rent sugars as carbon-sources for ureumsplitters; the species which are 
most remarkable generally agree with the powerful species isolated 
by Mriqurr. 
A culture-liquid consisting of : 
100 water 
0.05 K,HPO, 
1 ammoniummalate 
5 ureum 
infected with + two gr. of mould or sewage and cultivated at 
+ 33° contains after 48 hours, sometimes even after 36 hours 
only ureum-splitting ferments. A total supplanting of all other 
organisms has taken place in that short time. 
The decomposition of the ureum takes place in presence of easily 
assimilated carbonsources, such as malate and lactate, more rapidly 
than with compounds which are not so easily assimilated such as 
tartrate or acetate. 
Malate is also for these organisms an exceedingly easily assimilable 
compound, as is generally the case; lactate, citrate, succinate, tartrate, 
butyrate and acetate follow next. 
When, however, in a culture with one of these salts the final titre 
has been reached, the same powerful species are on the whole 
observed in malate as well as in tartrate and acetate cultures. 
Now if we examine the sorts succeeding each other in these culture- 
liquids, it appears that, when sown upon meat-gelatine '/, °/, ureum 
or ammoniummalate-gelatine */,°/, ureum, already after two days, 
when the titre is + 60 cc. N. per 100 ec. culture-liquid, the num- 
ber of micrococcis and melting bacteria rapidly diminishes; whilst 
the alkalinity increases, bacteria forming spores together with a 
ureum-splitter not forming spores take their place. 
The many weak splitting organisms observed in the cultures 
with calciumsalts rapidly die off. 
After 3 or 4 days only very strong hydrolysing microbes are 
left, whilst micrococcis and melting species have disappeared. 
The growth on neutral meat-gelatine of the species found in 
strongly alkaline liquids is very slight or does not sueceed at all. 
