262 Seventeenth Annual Report of the 



it does not follow that other animals can successfully resist the 

 infection under all conditions. Carnivora, omnivora, solipeds and 

 human beings, and even birds that drink the warm milk of affected 

 cows, contract the disease, and accidental inoculation in wounds, 

 and experimental inoculations go to show that probably all warm- 

 blooded animals are susceptible. The habitual escape of animals 

 that do not divide the hoof appears to be due less to an inherent 

 resistance to the virus, than to the different conditions of life 

 which withhold them from direct exposure to accidental inocula- 

 tion. Cattle, using the tongue for the prehension of their food, 

 bring that organ constantly in touch with grass soiled by the feet 

 or saliva of affected cattle or sheep, and as the fibrous food, espe- 

 cially in winter, causes frequent wounds and abrasions of the 

 surface, the virus is directly inoculated in the raw sores so pro- 

 duced. The feet of animals are similarly wounded by thorns, 

 stubs, shaly stones, and above all by the tufts of grass or other 

 vegetation which have been first smeared with the infecting liquids 

 coming from the ulcers in the arch of the cleft between the hoofs 

 of diseased animals that have preceded them, or the saliva that 

 has driveled from their lips, and then been drawn forcibly between 

 the hoofs. These last conditions affect the smaller ruminants and 

 swine and, indeed, all cloven footed races equally well. In cattle 

 the tongue is used not only as a hand in taking in food, but also 

 as a brush or rasp to relieve itching or pain, and when the feet 

 constitute the seat of the disease, the ready tongue is used to lick 

 them, transferring infection to the mouth, the udder or elsewhere. 

 Another potent accessory cause of infection in milch cows is the 

 hand of the milker or the mouth of the calf. If one cow has the 

 blisters on the teats all other cows handled after that one by the 

 same person, and with unwashed hands, can hardly fail to be 

 infected. Any cow with sores, chaps, or warts on the teats, and 

 any one wounded by the misused nails of the milker must in- 

 fallibly be inoculated. 



These special conditions of exposure to infection in the cloven 

 footed animals must not, however, be allowed to obscure the truth 

 that these animals have a higher receptivity to the poison than 

 others, and that of all parts of their body the mouth, mammary 

 glands and feet are the most susceptible points. 



