330 
cury, the tube B is filled with the culture, 
when the rubber stopper holding the side- 
tube d and straight tube d is tightly in- 
serted. When this is done the end of d, 
which serves for the escape of air dis- 
placed by the stopper, is sealed in the 
flame. The gas generated in B escapes 
into the closed arm A, displacing the mer- 
ecury. To determine the CO, ratio, the 
tube B is filled to the rubber stopper. Two 
fermentation tubes are used. In one, the 
arm A is filled with mercury, and the other 
half of the arm is filled with a saturated 
solution of sodium or potassium hydrate, 
this being readily accomplished by inclining 
the U tube towards the operator. The CO,, 
passing through the caustic solution, is 
absorbed, and the unabsorbed gas (H) is 
left. The ratio between the two is then 
determined. This apparatus is manufac- 
tured by Eimer and Amend, New York. 
A New Method of applying the Rabies Test : 
Cuas. F. Dawson, Detroit, Mich. 
The author, in his work upon rabies, was 
dissatisfied with the current method of in- 
oculating animals in the cerebrum, which 
involved trephining the animals, with occa- 
sional death from hemorrhage, possibility 
of self-inoculation and other difficulties. 
He has, therefore, devised a method of in- 
oculation in which these difficulties are re- 
duced or eliminated. The method is as 
follows: A bit of the brain of the suspected 
animalis ground in a mortar containing ster- 
ilized 6-per-cent. sodium solution, and is 
then filtered through sterilized cotton, Two 
minims of this solution are then injected 
on the base of the anterior cerebrum by way 
of the optic foramen. To accomplish this, 
full grown rabbits are used which are thor- 
oughly anesthetized with ether. A hypo- 
dermic syringe is used with a needle seven- 
eighths of aninchlong. The inoculation is 
made by lifting the nictitating membrane 
out of the way by means of the syringe 
SCIENCE. 
[N.S. Vou. XIII. No. 322 
needle, and then forcing the needle upwards 
and backwards through the orbital tissues 
until it enters the optical foramen. The 
contents of the syringe barrel are then in- 
jected and the needle carefully withdrawn. 
By this means the solution is injected un- 
derneath the cerebrum and the chances of 
injury to the animal are much lessened. In 
a series of comparative tests made with this 
and the ordinary method, the author reaches 
the conclusion that the new method is fully 
as satisfactory as the old, and much easier 
to apply. 
The Use of Carbolic Acid in isolating the Ba- 
cillus Coli Communis from River Water : 
WiiiAm B. CopeLann, Pittsburg, Pa. 
The author described a method which he 
had devised for the purpose of separating 
the coli bacillus in river water, by the use 
of solid media. For this purpose he used 
Wurtz’s agar, inasmuch as it could be incu- 
bated at 37° and the acid colonies were 
readily distinguishable by the reddening of 
the litmus. Inasmuch, however, as many 
other bacteria are present in river water, 
especially after a rain, which can develop 
at 37°, it is quite desirable to devise some 
means by which they may be reduced with- 
out affecting the colon bacillus. The author 
accomplishes this by adding to the agar 
two-tenths ec. of a 2-per-cent. solution of car- 
bolic acid. Experiments showed that such 
addition of carbolic acid reduced the total 
number of bacteria about 45 per cent., while 
it had no effect, apparently, upon the colon 
bacillus. This makes it possible to deter- 
mine the number of colon bacillus in water 
much more readily than if all bacteria are 
allowed to grow. By the use of this method; 
a study of the relation of the muddiness of 
river water and the number of colon bacilli 
was made. The result showed that, leaving 
out certain irregularities due to abnormal 
conditions, the number of colon bacilli in- 
creased with the turbidity of the water, a 
