IMMUNITY IN PNEUMOCOCCAL INFECTIONS 29 



the general reaction of the organism and stimulation of the defensive 

 apparatus by the bacterial irritant. 



During the Evolution of the Disease. — The usual number is about 

 18,000 to 24,000 per c.mm. The maximal leucocytosis is always about 

 the first day or two, and it diminishes slightly afterwards. 



Terminal Leucocytosis. — In cases undergoing rapid resolution there is 

 usually a sudden rise in the number of leucocytes just on the eve of the 

 temperature-fall, by about 2000 to 6000 : on the day of the crisis the 

 number is much reduced, and the day following is almost always nearly 

 normal. In cases terminating by lysis, the rise in leucocytosis just before 

 the crisis usually fails to occur. In complicated or fatal cases the 

 leucocytosis may not fall to normal, but go on increasing until the fatal 

 end. With very severe infections, however, or in patients with poor 

 resistance, alcoholic patients, etc., acute pneumonia may run its course 

 without any leucocytosis whatever. 



On a single intravenous inoculation of pneumococci, there is a 

 pronounced leucocytosis in five hours. In acute lobar pneumonia the 

 researches of Prochaska (32), Cole (33), and Frankel (34), show that the 

 pneumococcus can be very frequently isolated from the blood of patients 

 suffering from typical acute croupous pneumonia, if sufficient quantity of 

 the blood is removed, at least 10 cc. being required. It would seem as if 

 there were discharges, slight and at frequent intervals, of pneumococci 

 into the pulmonary capillaries and veins from the morbid lung, a 

 condition of bacteriaemia excited with pronounced stimulation of the 

 haemopoietic organs and a high degree of leucocytosis. The leucocytosis 

 is to be regarded as the cellular reaction product of the organism on 

 infection, the anti-bodies produced in the serum being the humoral 

 reaction products. 



Agglutination Phenomena in Acute Croupous Pneumonia. — In this 

 affection there are two separate agglutination phenomena witnessed — 

 agglutination of the red blood corpuscles, and bacterial agglutination. 

 The commoner and more uniform is the chromocytic agglutination, of 

 which some mention may be made. 



Wharton Jones (35) stated that in the blood of inflammatory diseases 

 " the rouleaux are formed more rapidly, and run into masses which have 

 large spaces between them, and thus the buffy coat is produced by this 

 close aggregation and more rapid subsidence therefrom resulting." If 



(393) 



