SIGNIFICANCE OF PHENOMENON 355 



The reaction occurring at inlectcd foci follo^ving parenteral 

 injection ot the bacterial antigen is usually very severe. The 

 lesions sho^v edema, congestion, ecchymosis, vascular stasis, nec- 

 rosis, sloughing and in some instances scar formation. The focal 

 reactions occur characteristically in the more vascular tissue of 

 the lesion. The tuberculin-killed animals show hemorrhagic exu- 

 date in serous cavities and diffuse congestion of serous membranes. 

 The peritoneum shows ecchymosis and rings of hemorrhage siu- 

 rounding indi\ idual tid)crcidous lesions. The pictme as described 

 by Koch is essentially that of intense hemorrhage and inflain- 

 matory reactions at the sites of all tuberculous lesions. 



The outstanding featine of bacterial hypersensitiveness is that 

 it is regidarly produced by spontaneous and induced infections 

 with living microorganisms and possibly viruses. The skin of tlie 

 infected guinea pig may become tuberculin positi\e on the sixth 

 or seventh day follo^ving the injection of the tubercle bacilli but, 

 as a ride, on the ninth to t^velfth day. Tissues in close relation 

 to sites of infection become more sensitive than tissues else^vhere. 

 In Stewart's (1925) experiments guinea {)igs ^vere infected by in- 

 jections into one testis and then tested by injection of tidjercidin 

 into both testes and intracutaneously. Positi\e reactions ^vere ob- 

 tained by the third day in the infected testes, on the sixth day 

 in the other testes and only on the eleventh day in the skin. Thus, 

 bacterial allergy Avhich is initiated in the lesion develops in the 

 entire host after a definite lag period. Follo^ving this lag there 

 appears, ho\vever, a state of marked sensitivity incidentally to 

 rapid increase of the number of tid^ercidous foci. As stated by 

 Tytler (1930), it may be considered that allergy develops pro- 

 gressively and that its development is controlled by quantitative 

 factors of which the most important is the extent of the exposine 

 of tissues to contact ^vith tidjercle bacilli. 



The sensitivity to tidDerculin continues at a high grade until 

 the final stage of the disease. Decreased sensitivity is, ho^vever. 

 observed dining intermittent periods of lowered vitality and dur 

 ing the final stages of the disease. Loss of sensitivity also accom- 

 panies arrest of the disease. Kraiise (1916-17) , ^vho produced local- 

 ized lesions ^vith an avirulent strain R-I in guinea pigs, obtained 

 negative tuberculin reactions when healing occurred. The tuber- 

 culin allergy may also fail temporarily during some active second- 

 ary diseases, i.e., measles (Preisich and v. Pirquet) ; chicken pox 

 (Schonfeld) ; puerperal infection (Nobecourt and Paraf, etc.) . 



