OTHER GERM DISEASES 449 



is partly due to the fact that the lung cells may be covered 

 up by the growth of the germs ; the chief danger, however, 

 is from the toxin, which may stop the action of the heart. 



We have already learned that malaria is carried by certain mos- 

 quitoes (cf. 424) ; yellow fever is carried in the same way. But while 

 one variety of mosquitoes (anopheles) carries the germ of malaria, an 

 entirely different variety (stegomyia; steg-o'-mi-ya) carries the yellow 

 fever germ. Yellow fever has long been the pest of tropical and sub- 

 tropical countries, and has been greatly dreaded in our own southern 

 states. When the United States took up the administration of Cuba, 

 in 1898, it had before it the problem of a general "cleaning up," and of 

 getting rid of the yellow-fever mosquito. It had the same problem to 

 solve before it could dig the Panama Canal. If houses, especially 

 those in which there is yellow fever, are carefully screened against 

 mosquitoes, and if the breeding places of the mosquitoes are destroyed, 

 the disease can be kept under control. 



Tetanus (tet'-a-nus), or lockjaw, is a. disease we hear most about 

 after the celebration of an " insane" Fourth of July, when there have 

 been many accidents with toy pistols, firecrackers, toy cannon, and 

 fireworks. The skin is so good a protection for the body that although 

 tetanus germs are often on the skin they do not get into the body. 

 But flying particles of the "caps," wads, and paper of explosives carry 

 the germs through the skin. The toxin produced by the germs is very 

 powerful, causing a contraction and stiffness of the muscles, first of 

 those of the face, and afterwards of those of other parts of the body. 

 Hence the name "lockjaw." Tetanus germs grow in the ground, and 

 away from the air, hence they may be present on rusty nails and un- 

 clean garden tools. Wounds made by articles that have been in or on 

 the ground should be dressed carefully, by a physician if possible. 



Rabies (ra -be-ez), or hydrophobia, seems to be produced by pro- 

 tozoa that grow in the nerve tissue of the brain and spinal cord. The 

 disease is "given" to dogs and cats in the bites and scratches which 

 they receive from other creatures that have the disease. The infected 

 dogs and cats give the disease to man. 



The Pasteur treatment for rabies is to cultivate the germs, so as to 



