lo Aug., 1912.] Tlie Etiology of Contagious Diseases. 



497 



the sheath, extt^iiding along the abdomen. From 40 to 45 days after 

 plaques are noticed on the skin (Fig. r8). The duration of these is very 



,.-<srs«ar/:-: '•■,.. 



FIG. 19. HORSE SUFFERING FROM DOURINE AT THE END OF THE SECOND 



STAGE. 



variable; wasting then sets in, the animal can rise only with difficulty, 

 and the limbs are paralyzed (Fig. 19). The duration is usually from two 

 to six months. In excep- 

 tional cases it lasts from one 

 to four years. It has been 

 recorded that certain breeds 

 of horses can retain the 

 power to spread the disease 

 in their system for one or 

 four years. It is estimated 

 that 70 to 80 per cent, of 

 affected mares die of the 

 disease in India. 



" Nagana," another of 

 these diseases, occurs in 

 horses, donkeys, oxen, dogs, 

 and cats, and varies in 

 duration from a few days or 

 weeks to many months. It 

 is invariably fatal in horses, 

 donkeys, and dogs. It is 

 present almo.st throughout 

 the whole of Africa, except 

 Cape Colony and the Trans- 

 vaal. 



Glanders, which all are 

 familiar with by name, can, fig. 20. bacillus of glanders penetrating 

 fortunately, be detected in wall of pulmonary artery. 



