100 PRACTICAL ZOOLOGY 



from one person to another by the tsetse fly (Fig. 58, A). In- 

 fantile paralysis is a disease that is often epidemic in this coun- 

 try. The results of recent investigations have proved that it 

 may be transmitted from a diseased monkey to a healthy one by 

 bites of the common stable fly, and it seems very probable that 

 these flies also transmit it from one human being to another. 

 The stable fly (Fig. 58, B) is frequently abundant around houses 

 and is often mistaken for the house fly; bites often credited to 

 the latter are really made by the stable fly, since the house fly 

 cannot pierce the skin (see page 76). 



Anthrax is the most widely spread of all infectious diseases. 

 It occurs almost all over the world, and attacks man, horses, 

 rabbits, and other mammals, but especially cattle and sheep. 

 The bacillus (Fig. 48, D) is comparatively large, being about 

 -g^Vfr of an inch long. Anthrax is especially interesting, since it 

 was the first disease proved (by Pasteur and Koch) to be caused 

 by bacteria. Blood-sucking flies are probably concerned in the 

 transmission of the anthrax germs, since the bacilli often enter 

 the body in wounds and are found in the blood of most of the 

 infected animals. Vaccination according to the methods de- 

 vised by Pasteur in 1881 is employed for cattle and sheep in 

 infected districts with good results. In France alone, between 

 the years 1882 and 1907, 8,000,000 sheep and 1,300,000 cattle 

 were vaccinated. 



Bedbug and Disease. The guilt of the bedbug, so far as 

 the transmission of disease germs is concerned, has not been 

 fully determined. Bedbugs (Fig. 58, C) are thoroughly domes- 

 ticated, living only in human dwellings. During the day they 

 hide in cracks, but at night they sally forth to suck the blood of 

 any unfortunate being that they chance to find. Gasoline, cor- 

 rosive sublimate, or turpentine, if injected into their hiding 

 places, will kill them. Bedbugs are accused of transmitting the 

 germs of leprosy, Oriental sore, and the dumdum fever or kala- 

 azar of the tropics. 



Sucking Lice and Disease. The sucking lice that occasion- 



