102 CLINICAL BACTERIOLOGY AND 



multiplied. To 10 c.c. of melted 3 per cent, agar rendered 

 acid by hydrochloric acid, add 5 c.c. of fresh sterile ox 

 serum, and pour into a Petri dish. 



Now spread a loopful of the acne-bacilli-laden broth over 

 the surface of the plate, and incubate for three days 

 (anaerobically) . These may be picked off, replated, and 

 incubated aerobically, and a bacterial emulsion made in the 

 usual Avay preparatory to the making of the vaccine. 



Follicular Mange in the Dog. 



This troublesome skin disease of the dog is due primarily 

 to the burrowing of the Demodex folliculorum. 



In course of time the protective forces of the skin suffer 

 considei'ably, the animal's health becomes impaired, his 

 opsonic index falls, and the patient is ripe for any bacterial 

 invasion that may come along. 



On the surface of the skin is to be found an excellent 

 medium for bacterial growth — blood-serum ; and at a body 

 temperature staphylococci soon manifest their presence by 

 excessive pus formation — so much so that, in advanced 

 cases, the writer strongly believes one's greatest concern, so 

 far as a cure goes, is to get rid of the bacteria, and that 

 the acari are but secondary factors at this stage in the 

 causation and continuation of the disease. 



An animal in such a condition is clearly one for the 

 immunizer, provided he can use an autogenous vaccine. 

 The obstinate nature of these cases toward orthodox thera- 

 peutics lies, not so much in the fact that the acari and the 

 bacteria are so difficult to destroy, but rather they are so 

 ungetatable (if one may use the word), their unassailable 

 seat being principally at the roots of the hair follicles. It is 

 quite obvious, then, to reach them one must use strong 

 penetrating poisons, which, as already indicated (in previous 

 chapters), when dealing with bacterial infections, is to be 

 deprecated, destroying as they do the very elements we 

 wish to preserve and fortify, i.e., the bactericidal antibodies 

 of the blood. 



