l8o MANUAL OF BACTERIOLOGY. 



invading army and the leukocytes or phagocytes to a force 

 designed to repel their attacks. 



It is certain that in some infectious diseases the number 

 of leukocytes, chiefly of the polynuclear neutrophilic variety, 

 in the circulating blood is increased (leukocytosis). This is 

 the case usually in lobar pneumonia and acute suppurative 

 infections. In other infectious diseases there is no leukocy- 

 tosis; for example, tuberculosis, typhoid fever and malaria. 

 It is interesting to observe that in trichinosis, and more rarely 

 in infection with other animal parasites, the eosinophiHc leuko- 

 cytes become much more numerous in the blood than normally. 



Experiments have been made by various investigators, con- 

 sisting in the proc^uction of local leukocytosis, and studying 

 the effects of the leukocytes thus brought together upon bac- 

 teria. The injection into the pleural or peritoneal cavity of 

 various substances, notably nucleic acid, or aleuronat suspen 

 sions, calls forth a great accumulation of leukocytes, and these 

 masses of leukocytes have been used for the purpose of observ- 

 ing the phenomena of phagocytosis both inside and outside the 

 body.* 



In operations upon the abdominal cavity the production 

 of artificial leukocytosis in the peritoneal cavity previous to 

 operations has been suggested and tried with apparent success 

 on the ground that if any bacteria entered during the operation 

 they would be destroyed by the phagocytes. f 



Wright and Douglas J found that certain substances prepare 



* Gustav F. Ruediger. The Mechanism of Streptococcus Infection. Jour- 

 nal 0/ (he American Medical Association. No. 3. January 21, 1905. P. 198. 

 Ludvig Hektoen and Gustav F. Ruediger. Studies in Phagocytosis. Journal 

 oj Infectious Diseases. Vol. II., No. i, p. 128. January, 1905. 



t Von MikuUcz. Versuche tiber Resistenzvermehrung bei Magen- und 

 Darmperforationen. Archiv jiir klinische Chirurgie. Bd. LXXIII., Heft 2, 

 p. 347. 1904. 



t A. E. Wright and Stewart R. Douglas. An Experimental Investigation 

 of the Rdle of the Blood Fluids in Connection with Phagocytosis. Proceedings 

 of the Royal Society. Vol. LXXII., No. 483, p. 357. October 31, 1903. Ibid. 

 Vol. LXXIII., No. 490, p. 128. February and March, 1904. 



