6 BULLETIN 340, U. S. DEPARTMENT OF AGRICULTURE. 
The inoculations should be made subcutaneously. Intravenous 
injections as first employed by Sclavo are less effective. The potency 
of the anthrax sermn is in no way increased by this method of 
immunization. Besides there exists the danger of emboli when in the 
later stages of the immunization process larger amounts of culture 
material have to be administered. Animals which have been treated 
with subcutaneous injections will produce finally an anthrax serum 
of remarkably high potency. 
As a rule the animals which have received one to two agar cultures 
show a specific protective action of their serum, but for practical 
purposes it is not advisable to use such a serum. Generally only 
when the animals stand one-half to one mass culture is the potency 
of the serum sufficiently strong. A similar condition is manifested 
in animals used for the production of immune serums for other 
diseases, the individuals showing a varying response to the injection 
for the production of immune bodies, i. e.. an animal will at times 
produce a potent serum relatively early, whereas another with the 
same method of treatment will develop a serum of the same potency 
only after a considerably longer preparatory treatment. Accord- 
ingly, from observation it has been noted that sheep produce the 
most potent serum, and in this species of animals the individual 
differences are of almost no consequence, so that almost every animal 
produces a good anthrax serum. Horses also produce a potent serum, 
although single individuals may show great variations. The anthrax 
serum from cattle is quite potent, but in its protective value it does 
not equal horse and sheep serum. 
It is best to draw the blood 14 to 16 days after the last injection; 
an earlier bleeding should be avoided. Not infrequently it occurs 
that animals after an apparent recovery following the inoculation 
reaction and after a period in which they are free of fever on the 
eighth or ninth day suddenly develop a rise in temperature. This 
has been established by Sclavo and Burow. Then, again, repeated 
regular blood examinations showed that at this time and even later, 
up to the tenth and eleventh days following inoculation, occasional 
anthrax bacilli may appear in the blood of the animals in greater 
numbers. 
The bleeding is carried out in the ordinary way. and the blood is 
collected in large sterilized glass cylinders or similar receptacles of 
about 2 or 3 liters capacity. Seven or eight liters of blood may be 
drawn from cattle, about the same quantity from horses, and about 
1 to 1$ liters from sheep. After 2 or 3 days another bleeding is 
made. In this instance, however, only a small quantity of blood 
should be drawn. The animals resist these operations very readily. 
and after a lapse of 11 days they are ready for another injection, 
