SCARLET FEVER 239 



The cycle of development is suggestive of the development of 

 many of the protozoa. Stages of development exhibiting fusiform 

 amoeboid shapes can be seen, and pseudopodia can be detected in 

 the process of developmental stages suggestive of gametocytes; the 

 union of the gametes and the ultimate formation of the zygote can 

 also be discerned. 



After the tenth day these bodies cannot be very well discerned 

 in the tissues. 



There is reason to think that the parasites circulate in the blood 

 in variola. The contagion in variola is thought to be by inhalation. 

 It is certain that the disease can be produced by inoculation with 

 virus from a case of small-pox. The contagion exists in the scales, 

 pus cells, and excretions of patients ill with small-pox. 



If the virus of small-pox is introduced into a monkey and then 

 into a cow the disease produced is not variola, but vaccinia (Monk- 

 man). The hypothetical organism above described, cytoryctes, 

 becomes attenuated in the cow, so that it is incapable of producing 

 variola, but vaccinia. 



Rabbits, horses, and sheep are susceptible of inoculation with 

 the virus of vaccinia (see vaccination). Virus may be tested by 

 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 8-10 months. It is de- 

 stroyed at 57 C. in 15 minutes and easily by most disinfectants. 

 It has not been cultivated. Passive immunization has not been 

 achieved. 



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 



