264 THE FILTERABLE VIRUSES 



glycerine, drying and autolysis. It is destroyed at 5oC. in one- 

 half hour. The virus can be cultivated by growing bits of brain 

 and cord from a case dead of the disease in unheated ascitic fluid 

 to which bits of sterile tissue have been added; the growth is 

 anaerobic. It appears as tiny globoid bodies, singly, in pairs or 

 short chains. Appropriate staining will demonstrate them also 

 in the nervous tissues. 



Active artificial immunity and some passive immunity have 

 been obtained but these are not of therapeutic value. One 

 attack probably confers immunity. In the therapeutics of the 

 disease it is practicable to inject into the spinal column, the blood 

 serum of human cases that have recovered from the disease; this 

 indicates that virus-neutralizing bodies are formed during an 

 attack. 



Foot and Mouth Disease. An acute infectious disease of cat- 

 tle, characterized by a vesicular eruption in the mouth and around 

 the crown of the hoof. It may be transmitted to man by the 

 use of milk from infected cows. It is also directly communicable. 

 It has not been cultivated. It is filterable; it is said to be due 

 to the Cytorrycetes. It is destroyed at 5oC. in ten minutes, 

 easily by freezing and ordinary disinfectants. One attack gives 

 no lasting immunity but the blood is said to contain anti-bodies 

 immediately after the attack, which will be protective to other 

 animals. 



Trachoma. An infectious inflammation of the conjunctiva 

 with the production of minute but visible nodules on the under 

 sides of the lids. By some it is said to be due to a form of the 

 influenza bacillus, by others to an invisible virus. It is directly 

 communicable, filterable and transmissible to monkeys. It has 

 not been cultivated. 



Measles. An acute eruptive fever due to a filterable virus 

 which is found in the blood, buccal and nasal secretions. It is 

 transmissible to monkeys by inoculations of patient's blood, even 

 before the Koplik spots appear. It persists in the blood until 



