CLASSIFICATION OF DISEASES. 73 



clean it thoroughly, and rinse it in an antiseptic solution. Also 

 cleanse the wound and then replace the tube, 



VARIOLA. 



What are the synonyms ? 



Small-pox. 



Give the definition. 



It is an acute, febrile, contagious, and systemic disease, char- 

 acterized by eruptions on the skin and mucous membranes, which 

 follow^ a definite course. 



What animals may be affected ? 



This disease may be seen in the horse, sheep, pig, dog, goat, 

 and ox. 



How may the disease be divided for study ? 



Into three stages: 1, The stage of incubation; 2, the stage of 

 invasion, and, 3, the stage of eruption. 



Describe the stage of incubation. 



This is the time elapsing from the entrance of the poison into 

 the system and the first manifestation of the disease. 



In the horse about one week, four to six days in the cow, four 

 to seven days in the sheep, and from ten to fourteen days in man. 



What takes place during the stage of invasion ? 



This is called the initial stage, and is usually ushered in by 

 a chill, followed by symptoms of fever and catarrhal symptoms. 

 This stage lasts from twenty-four to forty-eight hours. 



Describe the stage of eruption. 



This stage is important and characteristic. Little red spots 

 make their appearance on the skin in various parts of the body; 

 soon little nodules present themselves, which rapidly develop into 

 vesicles filled with a clear, limpid fluid; these vesicles are peculiar, 

 having a depression in the centre, and are called umhilicated. 



In three or four days pustules take the places of the vesicles. 

 The pus dries on top, forms a scab, which after a time falls off 

 and leaves a cup-shaped cicatrix or pit. 



