308 



GENERAL SCIENCE 



intestines and blood, bacteria in sufficient quantity friendly to the 

 human system and enemies of foreign bacteria. 



Blood-poisoning bacteria are usually found in infected wounds, 

 the severity of the poisoning depending upon the point of infection 

 and the character of the tissues. 



The white corpuscles or leucocytes (lu ko sits) of the blood are 

 enemies of all blood-poisoning bacteria. Whether or not a person 

 has a severe case of blood poisoning depends entirely upon the 

 fighting power of the white corpuscles of the blood, which Metchnikoff 

 calls " the policemen or scavengers of the circulation." The fighting 

 ability of the white corpuscles depends upon the quantity of a certain 

 substance called opsonin, which nourishes them and gives them 

 an increased power of killing harmful bacteria. 



Opsonic Index. Since the fighting power of a white corpuscle 

 depends upon the amount of opsonin present in the blood, the 

 opsonic index is taken to determine the fighting power of the white 

 corpuscle which makes a person immune to disease. This is done 

 with a microscope. 



Blood is taken from a person and washed with a weak solution 

 of acetic acid to remove the red corpuscles. The white corpuscles 

 are then observed. If one white corpuscle devours about one bac- 

 terium, the opsonic index is considered about -^ of 1 per cent. If it 

 destroys ten bacteria the index would be 1 per cent. The normal 

 opsonic index of the human blood is 1J per cent. Opsonin is often 

 added to the blood of patients when the opsonic index is below 

 normal. 



Pus-forming Bacteria. Certain bacteria, when grown in the 

 tissues, cause inflammation and form pus. These pus-forming bac- 

 teria cause boils, carbuncles, abscesses, erysipelas and blood poison- 

 ing. Tonsilitis and appendicitis are usually caused by these germs. 



Anthrax. Anthrax is an acute, infectious disease of domestic 

 animals, particularly ruminants and horses. 



History. The disease was known by its present name in the 

 oldest times (from the Greek word meaning coal) on account of the 

 black color of the blood. 



Anthrax has made its appearance the world over, outbreaks 

 occurring alike on the Siberian steppes and the moisture-saturated 



