70 Manual of Veterinary Microbiology. 



Microbes whose secretions attract the leucocytes * 

 will be more easily overcome by them, and will be 

 less dangerous for the economy. 



Microbes which repel the white corpuscles, finding 

 themselves in good conditions as to nutrition and 

 surroundings, will break down the barrier which the 

 corpuscles oppose to them. But, under conditions 

 unfavorable to their development, their secretions 

 diminish and the phagocytes regain all their power. 



Some agents, such as chloral and chloroform, are 

 capable of suspending the chemotaxic faculty of the 

 phagocytes. 



Certain influences — physical and moral disturb- 

 ances, fatigue, nervous perturbation, cold, which often 

 cause the irruption of an infectious disease or aggra- 

 vate it — have a depressing efiect upon the vaso-dilator 

 nervous apparatus, interfere with diapedesis, with 

 phagocytosis, and therefore favor the implantation or 

 multiplication of the germs of disease. 



2. Bactericidal or microbicidal property. — By the bac- 

 tericidal property is meant the peculiar quality of the 

 humors of the economy — blood, aqueous humor, peri- 

 cardial serosity, etc. — which impedes or prevents the 

 multiplication of pathogenic bacteria in these fluids. 

 This bactericidal faculty varies greatly according to 

 tlie species, the individual, and the germs with which 

 we have to do. When microbes are introduced into 

 the blood, a certain number of them perish ; those 



* [According to Buchner, the attractive action (positive chemo- 

 taxis) exerted by sterilized cultures of certain microbes toward 

 leucocytes is dependent on the proteid contents of the bacterial 

 cells, rather than on their secretion products. Baumgarten's 

 Jahresbericht, 1890.— D.] . 



