1148 
that the above mentioned species do not wel develop and often 
quite disappear. 
At infection with pasteurised soil (5 minutes at 80° C.) no growth 
takes place, which shows that to the spore-forming bacteria no 
paraffin-oxidising species belong. 
Under anaerobic conditions paraffins are not broken off by bacteria. 
Description of the paraffin-ovidising mycobacteria. 
These bacteria are immotile; in young cultures (8 hours on broth 
agar at 30° C.) they are rod-shaped, length 4—10%, width 0.5 1)— 1.5 4, 
after division it often occurs that the two individuals are still jomed 
in one point. 
Very characteristic is the appearance of ramifications in these 
microbes, which remind of bacteroids such as are found in B. radicicola. 
After some days’ culture en broth agar or broth gelatin, these 
rod-shaped bacteria pass into Streptococcus-like organisms, the cells 
of this form having a diameter equal to the width of the rod form. 
The Streptococcus-form produces, on a new medium, first the rod 
form, which then again passes into that of the Streptococeus. 
Spore formation does not occur; heating during 5 minutes at 
65° is not resisted. 
All species secrete some slime. The growth of the mycobacteria, 
which after their pigment-forming power on potatoes or on broth 
gelatin are distinguished in Mycobacterium phlei LeaMann and 
Neumann, M. lacticola L. and N., M. album, and M. rubrum, 
varies very much on different media as is shown in the table below, 
where some of the results on growth and pigment formation are given. 
On potato these microbes form most pigment *) and grow very 
well; likewise on broth-, malt-, und glucose gelatin. A very good 
medium is also broth gelatin or broth agar with 3°/, glucose. 
Besides on the above substances the fat-splitting bacteria and the 
Mycobacteria grow on humus compounds without these being deco- 
loured. The best source of carbon is peptone, then follows aspara- 
gin, ammonium chlorid, and potassiumnitrate. Nitrate is reduced to 
nitrite ; denitrification does not take place. In broth, with 3°/, pep- 
tone, indol is not formed. 
In broth with 3°/, glucose, no fermentation is observed. 
Tyrosin is not changed into melanin. 
1) The pigment of Mycobacterium rubrum is probably carotine ; it resists 
hydrochlorid (38 °/,), potash solution, and ammonia, dissolves in chloroform and 
ether and is coloured dark blue by sulfuric acid of density 1,86. 
