The Effect of Specific Vaccines in Typhoid. 109 
In our own studies we used guinea pigs averaging about 400 
grams in weight and sensitized by subcutaneous administration 
of 0.05 cc. horse serum. The atropin was injected intravenously 
five minutes before the toxic dose of horse serum which also was 
administered into the jugular vein. 
The study shows that as the toxic dose of horse serum is 
increased the protecting dose of atropin must also be increased, 
but the increase in protecting dose is not proportionate to that 
of the horse serum. The curve of protecting dose rises much more 
sharply than that of horse serum and finally a point is reached 
where the animal succumbs to the dose of atropin. A 400-gram 
guinea pig is killed almost instantly by a dose of 0.060 gram 
atropin. 
That the effect of the atropin is physiological and not due to 
any alkaloidal combination with the toxic fraction of the horse 
serum is shown by the fact that a mixture of atropin and horse 
serum incubated at 37 0 C. and dialyzed for four days killed 
sensitized animals whereas a control in the same proportions but 
not dialyzed saved the animals from anaphylactic death. 
66 (591) 
The effect of specific vaccines in the typhoid of rats and mice. 
By EDNA STEINHARDT and THOMAS FLOURNOY. 
[From the Laboratory of Hygiene, University of Michigan, and the 
Pathological Laboratory, Bellevue Hospital.] 
Owing to the impossibility of infecting small laboratory animals 
by feeding with typhoid bacilli, the immunity produced by specific 
vaccines has always been tested by subcutaneous or intra-peri- 
toneal inoculations of the living culture. 
These methods do not produce a disease comparable to human 
typhoid, but when rats and mice are fed with certain of the para- 
typhoid group they contract a disease whose pathology does closely 
resemble it; therefore these were used for the comparative study 
of the vaccines. The Danysz virus (one of the Gaertner group) 
was the test organism. 
White mice were used in the first series and the vaccines tested 
were killed cultures, Vaughan's residue, sensitized bacilli (Bes- 
