( 680 ) 
2. By a large number of bacteria, universally spread in nature, fats 
may be broken off anaérobically, oxydised aérobieally, or if nitrates 
ov nitrites are present be denitrified. 
3. All these processes are caused by the secretion of “lipase” 
by microbes; glycerin and fatty acids separated by the action of 
this enzyme are then further converted by the organisms. 
4. Several fat-splitting organisms produce two lipases, «- and 
B-lipase; the former diffases more rapidly than the latter and splits 
fat as well in an acid as in an alkaline medium; 3-lipase is formed 
in an acid medium but does not decompose fat in it; it may however, 
become active again after neutralisation of the medium. 
5. Lipase diffuses through water-free fat; but the diffusion velocity 
is very small. 
6. The aérobie fat-splitting bacteria thrive well in culture media 
containing exclusively fat as source of carbon and ammonium chloratum 
as source of nitrogen. 
7. To the already known fat-splitting bacteria we can add: 
Bacillus putrificus (Brexstock), a representative of the mesentericus 
group, B. Stutzeri, and B. denitro fluorescens non-liquefaciens. 
8. Milk is a favourable medium for fat-splitting microbes. 
9. In spontaneously infected milk, kept under circumstances 
usual in practice, growth and destruction of fat-splitting bacteria 
and lactic acid ferments occur about simultaneously; they are chiefly 
dependent on the acid production. 
10. The injurious influence of fat-splitting microbes on the quality 
of dairy products is chiefly owing, besides to their lipolytic properties, 
to the formation of bitter tasting and badly smelling products from 
proteids and casein by these microbes. 
This subject will be more elaborately treated in the “Centralblatt 
für Bakteriologie”. 
Botany. — “On the cause of dimorphism in Oenothera nanella.” 
By H. H. Zeirsrra Fzx. (Communicated by Professor Huco 
DE VRIES). 
In 1905 I oeeunied myself with an investigation of the dimorphism 
of Oenothera nanella which in consequence of many other duties 
before my departure to India, could not be completed. Although | 
intend fo continue this inquiry next year, I think it desirable already 
to communicate the following preliminary results. 
In “die Mutationstheorie” DE Vrits in a description of the species 
of Oenothera arisen by mutation has made us acquainted with a 
