84 



and test Iroiu time to time, by simply cultural methods,* whether or not the 

 bacteria are alive. Thus, in one experiment, there were mixed with human 

 serum tj'phoid fever germs in such numbers, that every drop of the serum 

 contained 50,000 bacteria. Two minutes later but 20,000 of these were 

 alive; at the end of ten minutes, but 800; and in twenty-five minutes, they 

 were all dead. 



Not only can serum kill bacteria, but most of the secretions of the 

 healthy human body are bacteria-killing as well. Gastric juice, vaginal 

 secretion and uasal secretion, kill bacteria in enormous numbers. The hy- 

 gienic significance of this is evident from the fact that these bacteria-killing 

 substances, also, are moditied by modes of life. Dietary excesses may so 

 lower the bacteria-kiiliiig properties of gastric juice, and unsanitary condi- 

 tions so lessen that of the tissue juices that susceptibility to infectious dis- 

 eases is greatly increased. 



The third way of hygienic imijortance in which the body fights disease, 

 is by phagocytosis. In the body there are millions of white blood cor- 

 puscles, each having the power of independent motion and as one of its 

 functions the faculty of eating and destroying disease germs. 



It is found that the bacteria-eating power of white corpuscles is largely 

 dependent upon certain chemical substancest present in the blood and 

 tissue juices. Without these chemical substances the eating of certain 

 pathogenic bacteria does not take place. With them, it is very active. It is 

 further found that these ciiemical substances are influenced by modes of 

 life. That they may be increased or decreased under difi'erent hygienic 

 conditions. Phagocytosis, therefore, has also a place in popular hygienic 

 linowledge. 



One of the unfortiniate results of the spread of knowledge of patho- 

 genic micro-organisms is the formrttiou of an unreasoning popular fear of 

 disease germs. It is thought tliat a wide understanding of facts regarding 

 bodily resistance will tend to rer)lace this unfortunate germ-fear by a 

 rational faith in tlie l)ody's marveloas powers. That it may turn the tide 

 of hygienic endeavor, from an exclusive fight against bacteria to a com- 

 bined fight against bacteria and for bodily resistance. 



"See Popular Science Monthly, Vol. 66, pp. 474-177. 

 t Opsonins. 



