DTSEASES OF QUESTIONABLE ORIGIN 195 



gum. The resistance of trees requires to be lowered 

 by fire or mechanical injury before the bacteria can work, 

 and it is thought that ants carry the gum-producing organ* 

 isms from tree to tree. 



For further information on phytopathology, see Jakob 

 Eriksson's * Fungoid Diseases of Agricultural Plants ' 

 (Bailliere, Tindall and Cox, 1912). 



CHAPTER XIX 

 DISEASES OF QUESTIONABLE ORIGIN 



Scarlet Fever. Streptococcus scarlatince (Klein), or 

 8. conglomerate, occurs in desquamating particles of skin, 

 blood, sputa, tissues, urine, and mucous secretion of the 

 throat of patients (see p. 134). Mallory has found small 

 rounded bodies resembling protozoa, which others regard 

 as degenerate leucocytes. They sometimes show rosette 

 forms and stain with methylene blue. Jordan regards 

 them as characteristic of the disease. Perhaps, at one 

 stage at any rate, the virus is filterable. 



The disease is more prevalent in the northern part of 

 Europe than in other parts of the Continent. Epidemics 

 exhibit a quinquennial recurrence, the mortality being 

 about 3 per cent., and greatest at the age of five. One 

 attack is usually protective. 



Formerly the chief danger of dissemination was thought 

 to lie in the desquamating particles of skin, but the faucial, 

 nasal, and aural secretions are now regarded as the more 

 important sources of infection. Milk is a frequent medium 

 for the conveyance of the disease. Much difference of 

 opinion exists as to whether the disease can arise from a 

 bovine source. 



Malignant Disease. Hitherto, although a large number 

 of organisms have been described, none has been shown 

 to produce either carcinoma or sarcoma. According to 

 Rous, the aetiological agent of a spindle-celled sarcoma 

 in chickens proved to be a filterable virus. * *, 



Epilepsy. Reed thinks this disease is an infection with 

 a gas-producing^bacillus. 



Pellagra. Sambon believes this to be of protozoan 



