PAPERS ON MEDICINE AND PUBLIC HEALTH 327 



collapse after a second injection and local necrosis after 

 repeated injections. Failure to get in man the typical 

 picture frequently observed in experimental animals may 

 be due to the relatively smaller doses given, the usual 

 dosage being much lower per unit body weight than 

 necessary to cause shock in animals such as the guinea 

 pig. In case of intravenous and intraspinous injection 

 in man the factor of quick absorption must not be lost 

 sight of and guarded against. 



Hyper sensitiveness and Infection. — In many com- 

 municable diseases there develop varying degrees of 

 hypersensibility to causative agent. The most exten- 

 sively studied and best known examples of this are in- 

 fections due to the tubercle and the glanders bacillus. 

 Tuberculin, which consists of the soluble products found 

 in a broth culture of the tubercle bacillus, is only toxic 

 for an infected animal, i.e., infection results in hyper- 

 sensitiveness. Such hypersensibility may be demon- 

 strated in the skin, mucous membranes and also by a 

 systemic and focal reaction (site of lesion) when in- 

 jected in sufficient doses. Too large a dose may result 

 in death of the sensitive animal. Tuberculin is highly 

 resistant to heat, and is specific but not anaphylacto- 

 genic. A relative tolerance may be induced in the tuber- 

 culous animal by gradually increased doses. This sub- 

 stance differs further from all similar substances in that 

 animals cannot be rendered hypersensitive by its injec- 

 tion experimentally. On the other hand, the proteins of 

 the tubercle bacillus are anaphylactogenic. This is a 

 distinctly different phenomenon. The real mechanism of 

 the tuberculin reaction is still obscure. 



A similar skin reaction may be obtained in a consider- 

 able proportion of syphilitic cases by the intracutaneous 

 injection of "ruetin," an emulsion of the Treponema pal- 

 lidum. Indications of hyperseusitiveness have also been 

 noted in typhoid fever or following the injection of ty- 

 phoid vaccine. Likewise, positive skin reactions have 

 been found to follow the injection of the genococcus and 

 in such conditions as Leprosy, Sporotrichosis and other 

 diseases caused by fungi and in pregnancy. All these 



