262 THE FILTERABLE VIRUSES 



rubbing over the shaven bellies of rabbits, setting up minute 

 vesicles and finally crusts (Calmette). 



The two viruses, that of variola and that of vaccinia, are now 

 thought to be identical. In a diluted condition it is filterable. 

 It resists drying for weeks and glycerine eight to ten months. It 

 is destroyed at S7C. in fifteen minutes and easily by most dis- 

 infectants. Passive immunization has not been achieved. No- 

 guchi has succeeded in growing the virus in the testes of rabbits; 

 one of his objects in so doing was to afford a sterile cultivation of 

 virus which might be used for preparing vaccine. 



Scarlet Fever 



Mallory in 1903 found certain bodies in the skin of scarlet fever 

 cases. These bodies, he assumed, were protozoan in character 

 and were the etiological cause of the disease. He named them 

 Cyclasterion Scarlatinale. They have been found rather con- 

 stantly in the skin of scarlet fever cases, also in the skin in cases 

 of measles and in anti-toxin rashes. Dohle has also described 

 an inclusion body within the polynuclear leucocytes. By several 

 observers these bodies have been considered to be artefacts or 

 degeneration products in the epithelial cells. 



The virus of scarlatina is now considered to be filterable and 

 transmissible to monkeys. Mallory has lately found diphtheroid 

 bacilli in great numbers in the pharynx in scarlatina and believes 

 they may be its cause. Virulent streptococci, usually of hemoly- 

 tic quality, are so frequently encountered in the respiratory tract 

 and in complications during scarlet fever that many persons look 

 upon them as the cause; this cannot be proven as the disease 

 cannot be successfully transmitted to lower animals by use of these 

 organisms. 



Dengue Fever. This is an acute infectious disease of the 

 tropics, characterized by fever, skin eruptions, rheumatoid pains, 

 an afebrile remission and a febrile end, due to a filterable virus, 



