636 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
means of alcohol. Tuberculous animals also react with succinic acid, 
while per os neither tuberculin nor succinic acid has any effect. Animals 
affected with Echinococcus react to tuberculin, and this is not to be 
wondered at considering that these cestodes contain succinic acid. If 
tubercle bacilli are heated to 180°, crystals of succinic acid are formed, 
and these are quickly dissolved in acidulated ether. Succinic acid, then, 
plays the principal part in tuberculosis and tuberculin. TO or TE is 
nothing else than an aqueous solution of an alkaline succinate, of little 
commercial value, and obtainable of any chemist. Full details are 
promised later. 
Variations in the Liquefying Power of Milk Bacteria.* — Prof. 
H. W. Conn describes two series of experiments with milk bacteria, 
which show that conditions in nature can produce wide differences in 
their physiological properties. Two examples are dealt with. The 
first, a micrococcus, was found in all the specimens of the milk and in 
the air of the cowshed. Under the same conditions another coccus was 
found in equal abundance, the only difference between the two being 
that the latter did not liquefy gelatin. Their principal common feature 
was yellow growth on gelatin-agar and potato. Milk was curdled at 
36° in three days with an amphoteric reaction. 
The curd was subsequently little or not at all digested. Further 
researches established the fact that there are numerous gradations 
between the two cocci, and that apparently they are natural varieties 
of one species. Later on analogous variations were noticed as to the 
colour ; many of the colonies were white or wdntish-yellow, and these 
were also found under natural conditions. The second bacterium was 
a bacillus which produced yellow and white colonies. This possessed 
general characters resembling those of Bacillus lactis erythrogenes, ex- 
cept the red colour, but when inoculated on agar the medium assumed 
a rose-pink tinge. Just as in the case of the coccus, the two varieties 
of the bacillus remained true, the one liquefying and the other refusing 
to do so. The conclusion seems therefore clear that they must be 
varieties of the same organism, and if so, then there are numerous pro- 
blems in natural environment yet unsolved. 
Chemical and Bacteriological Examination of Water and Sew- 
age.f — The committee appointed by the British Association to establish 
a uniform system of recording the results of the chemical and bacterio- 
logical examination of water and sewage, suggest in an interim report 
that in the case of all nitrogen compounds the results be expressed as 
parts of nitrogen per 100,000, including the ammonia expelled in boil- 
ing with alkaline permanganate, which should be termed albuminoid 
nitrogen. The nitrogen will therefore be returned as (1) ammoniacal 
nitrogen from free and saline ammonia ; (2) nitrous nitrogen from 
nitrites ; (3) nitric nitrogen from nitrates ; (4) organic nitrogen (either 
by Kjeldal or by combustion) ; (5) albuminoid nitrogen. The total 
nitrogen will be the sum of the first four determinations. The purifi- 
cation effected by a process will be measured by the amount of oxidised 
nitrogen as compared with the total amount of nitrogen existing in the 
crude sewage. 
* Centralbl. Bakt. u. Par., 2 te Abt., v. (1899) pp. 665-9. 
t Journ. Soc. Arts, xlvii. (1899) p. 835. 
