GENUS BACTERIUM 257 



veterinarian who applied it, but in the failure to have subse- 

 quent tests made. 



The skin and ophthalmic application of tuberculin. It 



has often been noted, especially in the human subject, that a 

 considerable degree of local irritation occurs at the site of the 

 injection of tuberculin in tuberculous patients. The signifi- 

 cance of this phenomenon was not fully appreciated until the 

 investigations of von Pirquet 22 on so-called accelerated reac- 

 tions in revaccinations against smallpox. This condition re- 

 called the well-known experiments of Koch which led to the 

 discovery of tuberculin ; namely, that in a tuberculous guinea 

 pig a second inoculation under the skin was followed by much 

 more swelling than the first and a rapid formation of a slough 

 without involvement of the surrounding lymph nodes as in the 

 primary infection. Von Pirquet 's attention was directed, in 

 consequence of this, to the effect of tuberculin rubbed into 

 scarifications of the skin. In 360 tests on children in the 

 Berlin and Vienna clinics it was found that a well-marked 

 difference was obtained in the reaction hyperemia between 

 tuberculous and non-tuberculous children under two years of 

 age, but in older individuals this was slight. The diagnostic 

 value, therefore, seemed to be limited to children. This method 

 was tried by Arloing 23 and Vallee 24 in cattle, rabbits and 

 guinea pigs, with uncertain results. 



In order to overcome the danger of injecting too much 

 tuberculin in making a diagnosis on the human subject a 

 method was simultaneously proposed by Wolff-Eisner 25 of 

 Berlin and Calmette 26 of Lille, France. The method consists 

 in putting a drop of weak tuberculin solution (1%) into the 

 eye, whereby a conjunctival hyperemia is produced in tuber- 

 culous individuals. This is due to the increased sensitiveness 

 of the tissues of tuberculous animals as compared with non- 



2 -V. Pirquet. Berliner klin. Wochenschr., May 20, 1907. 



23 Arloing. Compte rendu de la Soc. de Biol., June 28-29, 1907, 



21 Vallee. Ibid. July 12, 1907. 



25 Wolff-Eisner. Berliner klin. Wochenschr., June 3, 1907. 



28 Calmette. Presse medicale, June 19 and July 13, 1907. 



