AGf~ICULTURAL RESEARCH, PUSA.

184 PRACTICAL BAC1'EllIOLOGY
-------------introduced.
A_ 2 c.c. or a 5 c.c. syringe is cOllvenient
for the purpose.
I ntraperitoneal.--The animal is held in a similar
manner. The inoculation is made in the mid-line
in the lower half of the abdomen. Thu skin Inay be
sterilised. 'file assistant holds the animal with its
head downwards, so that the intestines fall towards
the diaphragm. 'rIle skin is pinched up, the point of
the needle passed into the :,mbcutalleous tissue, and
then downwards through the abdominal wall into
the peritoncal cavity. 'rherc is 110 risk of damage to
the intestines. Not more than 5 C.c. can safelv be
inoculated intra peritoneally . .
IntracutaneoH,s.-'I'his method is used chiefly in
testing cultures of the diphtheria bacillus for virulence
(vide p. 28G). 'rhe hail' is removed from the flanks of
the animal by meaDS of a depilating' powder Ol' a
fresh 5 PCl' ccnt. solution of sodium sulphide. White
guinea-pigs (300-400 grams weight) are used, as the
skin is unpigmented and the results of the test can
casily be read.
The depilating powder is made as follows:
Barium sulphide, commercial powder
White household Hour
rralcum powder
Castile soap powder
7 parts
7 parts
7 parts
1 part
Hemove the hail' from the flanks as closely as possible
with hair clippers. Make up the depilating powder
into a smooth paste with water, and rub into the
animal's hair with a wooden spatula or toothbrush.
Allow the paste to act for one minute and renew the
application. After two minutes remove the paste
with the spatula or handle of the toothbrush. Now
wash the animal's skin and surrounding hail' with
warm water and dry with a cloth. The depilated
surface should be quite smooth and white, and it is
not advisable to leave the paste on too long as the
skin becomes red and excoriated in patches, making
the subsequent reading of reactions very difficult. The