DISEASES FROM MICRO-ORGANISMS. 125 



vation for sixteen days. During the illness the dis- 

 charges from the mouth, nose, and intestines should 

 be disinfected. The quarantine must be maintained 

 until the skin is entirely free from crusts and scales. 



The method and principles of immunization to 

 smallpox have- been described under the subject of 

 immunity. 



CHICKEN-POX, OR VARICELLA. 



This is an acute infectious disease of children. It 

 is spread in the same manner as smallpox, but to pre- 

 vent its spreading the precautions need not be so 

 rigidly enforced, because it is not so> serious an infec- 

 tion. The patient is kept from contact with other 

 children, and after recovery the room should be 

 disinfected. 



RABIES, OR HYDROPHOBIA. 



Rabies is a disease common among animals, par- 

 ticularly dogs, although cats, cattle, and horses may be 

 infected. It is transmitted from one animal to an- 

 other, and to man through the saliva from the bites of 

 rabid animals. The poison acts upon the tissue of the 

 brain and spinal cord, being carried there along the 

 nerve-trunks. The incubation period is from forty to 

 sixty days. 



In animals the disease begins with a stage of ex- 

 citement and restlessness, followed by depression, diffi- 

 culty in swallowing, and paralysis. In man there is 

 first headache and depression, later difficulty in swal- 



