FILTERABLE ORGANISMS 2IQ 



cance by various authors. There is some evidence in favor 

 of Funck's belief that vaccinia is caused by a protozoon, the 

 Sporidium vaccinale. Animals inoculated with this organ- 

 ism developed both vaccinia and variola. It is possible that 

 the organism causing small-pox is a filterable one, and 

 beyond the present methods of research. 



Yellow Fever. For some years it was thought that a 

 bacillus, called Bacillus icteroides by Sanarelli, was the cause 

 of yellow fever. The earlier work of Sternberg was disproved 

 when it was shown that his bacillus, Bacillus X, was identical 

 with the colon group, and Reed and Carroll found that San- 

 arelli's germ was an allied organism. 



It is now known that a special species of mosquito, Ste- 

 gomyia fasciata, conveys the infection and acts as a culture- 

 medium for some unknown microorganism, possibly a proto- 

 zoon, which must undergo certain changes to become virulent. 



Only by the bite of a mosquito infected with the blood of a 

 yellow-fever patient or by direct inoculation of such blood can 

 yellow fever be transmitted. 



The experiments made so far show that the germ is de- 

 stroyed by a temperature of 55 C. for ten minutes. It can 

 pass through a Berkefeld filter, and is, therefore, extremely 

 minute, ultra-microscopic, but no one has as yet been able to 

 find any distinctive organism in the blood. 



Measles. Recent experiments (Anderson and Gold- 

 berger) demonstrated the virus in the nasal and mouth secre- 

 tions, and this secretion, collected forty-eight hours before 

 eruption, when inoculated into monkeys reproduced measles 

 in them. The infection was not possible forty-eight hours 

 after the eruption nor from the desquamation. 



Typhus fever, or Brill's disease, has a virus which is 

 non-filterable and which resides in the plasma of the blood. 

 Monkeys can be inoculated with the disease. Transmitted 

 by lice. 



Acute Poliomyelitis. The virus is contained in brain 

 and spinal cord and also in the mucous membrane of the 

 nose, in the salivary glands, and cerebrospinal fluid; it is 



