250 APPLIED IMMUNOLOGY 



a perfectly sharp pointed fine needle is employed, the 

 amount of pain occasioned by the puncture is ex- 

 tremely slight. The bacterin, if a large dose, should 

 be slowly injected into the loose subcutaneous tissue 

 to minimize pain. As the needle is withdrawn the 

 site of the pmictui-e should be compressed and the 

 skin gently stroked a couple of times with the pledget 

 of alcoholized cotton. No further dressing is neces- 

 sary or desirable. 



Dosage. — The size of the dose of bacterin must be 

 cautiously gauged. The two fundamental considera- 

 tions are ( 1 ) the nature of the particular infecting bac- 

 terium and (2) the condition or state of the patient. 

 It should be thoroughly realized that not only bacteria 

 in general but individual strains of the same bacterium 

 differ greatly in virulence and, as a rule, the more viru- 

 lent the microbe the smaller should be the inocula- 

 tion. To determine this and the inmiunizing power of 

 the bacterin, with the greatest precision, various clini- 

 cal laboratory and blood tests are essential. Thus the 

 dose of the more virulent bacteria, as the streptococcus, 

 pneumococcus, gonococcus, colon bacillus, etc., should 

 be considerably smaller, that is, one-half to one-fom'th 

 that of the less virulent microorganisms, as the staphy- 

 lococcus. Again, a most important problem is the de- 

 termination of the viiimnal effective and the average 

 and maocimal dose for each bacterium. In desper- 



