4S6 STUDIES IN IMMUNITY. 



used to immunize the animal less than it does another organism 

 from a different case of whooping cough. 



AW have hoped to be able to make a serum diagnosis of whoop- 

 ing cough by the simple and practical agglutination method. We 

 have found, unfortunately, that the serum of children suffering 

 from or convalescent of whooping cough shows very inconstant 

 agglutinating properties. An agglutinating property is frequently 

 distinctly manifest, although never very intense; it is often, how- 

 ever, entirely lacking. There are many sera which, although not 

 agglutinating, are distinctly sensitizing. As we have already men- 

 tioned, the alexin-fixation method always gives very marked positive 

 results. The two properties of agglutination and fixation are there- 

 fore quite separate in this disease. In this connection we may 

 recall that the serum from the convalescent case of typhoid fever, 

 with which we made our first attempts at alexin fixation (1901), 

 was also strongly sensitizing without being agglutinating, and we 

 have frequently noted this fact since that time. Various other 

 observers have also noted the lack of necessary parallel between 

 agglutination and bactericidal power. 



We have already noted the lesions .(excessive irritation and cloud- 

 ing of the cornea) which follow the injection of a sputum containing 

 the organism in pure state, or of a culture of the organism in the 

 anterior chamber of the rabbit's eye. Certain remarkable phenom- 

 ena are also to be noted on injecting the organism in the guinea-pig's 

 peritoneal cavity, and similar effects take place in the rabbit's peri- 

 toneal cavity if larger doses are employed. For this purpose an 

 emulsion of culture from blood agar 2 or 3 days old is better than 

 the less virulent fluid cultures. 1.5 to 2 milligrams of bacteria, 

 weighed in a moist condition, causes death on the following day 

 or on the second day. We have to deal here, not with an infection, 

 for the bacteria show no marked increase in the peritoneal cavity; 

 at autopsy only a few of the organisms are found in the exudate, 

 and frequently all of them are phagocyted by the large number of 

 leucocytes present. Intoxication phenomena, however, are very 

 marked, and are evidenced by the appearance of petechia? in the 

 peritoneal wall, and also at times in the pericardial cavity, and 

 by an extreme congestion of the cardiac blood vessels. Fatty 

 degeneration of the liver is also found. The most apparent symp- 



