SUMMARY OF CURRENT RESEARCHES RELATING TO 
of .the criteria, such as the number of flagella, the form and appearance 
of the young colonies, or the cholera red reaction have no specific value, 
and are only to be regarded as group characters. The experiments on 
man and animals show that the cholera vibrios are capable of producing 
the disease provided the other unknown conditions are present, and 
they further seem to show that the disease is rather an infection than 
an intoxication. There is no reason to suppose that the poison secreted 
by the cholera vibrio is specifically different from poisons formed by 
other bacteria ; and as to its exact nature we are still in the dark. After 
pointing out that experiments on animals have quite failed from a dia- 
gnostic point of view, the author sums up by affirming that the present 
position of the bacteriology of cholera is that we know with certainty 
that the vibrios occurring in the cholera process call forth the morbid 
phenomena, but that we cannot diagnose these vibrios as a definite spe- 
cies with certainty. No definite opinion can be expressed as to whether 
in all true cholera cases, the vibrios belong to one or to several species, 
nor whether they are different from our endemic vibrios or are identical 
with them. 
Behaviour of Cholera Bacilli in Aerobic and Anaerobic Cultures.* 
— Dr. Hellin made cultures of cholera bacilli in litmus whey (10 ccm. 
each) and incubated them for 5-8 days at 37°. The now red cultures 
required 0 * 7-0 • 8 ccm. of a 1/10 soda solution to restore the original 
colour. The cholera bacilli therefore form acid which, expressed in 
terms of the standard soda solution, is equivalent to 7 or 8 per cent. In 
the experiments a blue scum, 2-3 mm. thick, formed on the surface of 
the litmus whey, beneath this there was a layer of red fluid, while 
lower still the fluid was quite decolorised. The upper blue layer 
showed that the cholera bacilli made the medium alkaline, and as the 
scum cut off access of air to the parts below, there was in the same test- 
tube an aerobic and an anaerobic cultivation. There was no difference 
in the reaction after a stay of 10 days in the thermostat. When the 
cultures were placed in a Buchner’s apparatus for breeding anaerobes 
all the whey turned red, but no scum membrane w r as formed ; hence it 
follows that the different reactions in the first case depended on the 
presence or absence of air. Cholera bacilli are accordingly formers of 
acid and alkali, the latter corresponding to oxidation, the former to 
reduction. In the human alimentary canal, the cholera bacteria, when 
oxygen is excluded, form acid, and at the same time exert a reducing 
action. 
The author further states that in the presence or absence of oxygen, 
cholera bacilli form nitrous acid in the course of a few hours if 0*01 
grm. NaN0 3 and 1 per cent peptone be added to the medium. In 28 
hours 5 mg. of nitrite were demonstrated. The quantity of nitrous acid 
formed is greater, if the nitrate be added after the bacteria have started 
growing, than if put in before the inoculation. 
By introducing 0*01 cm. nitrate and cholera bacilli into an egg, it 
was determined that in one day 1 mg. N 2 0 3 was formed, in 2 days 2 mg., 
and 5 days 4 mg. A comparison of egg and bouillon cultures showed 
* Arch. f. Hygiene, xxi. (1894) p. 308. See Centralbl. f. Bakteriol. u. Parasitenk., 
l te Abt., xvii. (1895) pp. 764-5. 
