356 SPECIFIC MICRO-ORGANISMS 



the fresh drop of blood not only by direct central illumination 

 with a yellow light but also by means of dark-field illumination, 

 and to examine thin films made by mixing India ink 3 parts with 

 the blood i part and spreading very thin. Finally thin blood 

 films should be stained and examined. The inoculation of white 

 rats with i to 5 c.c. of blood conveys the infection to them and 

 the parasites appear in the blood of the animal 2 to 4 days after 

 inoculation. The spirochetes may vanish from the blood with 

 marvelous rapidity. 



Spirochaeta Anserina. Sacharoff in 1890 discovered this 

 spiral organism in the blood of geese suffering from a serious 

 disease in the Caucasus. Ducks and chickens are also susceptible. 

 The spirochete is about o.5/z thick by 10 to 20/1 long. It is con- 

 sidered by Nuttall to be indentical with the Sp. gallinarum of 

 Marchoux and Salimbeni. 



Spirochaeta Gallinarum. Marchoux and Salimbeni in 1903 

 discovered this organism in the blood of diseased chickens at 

 Rio Janeiro. The organism is 0.5/4 thick and 15 to 20^ long. 

 The disease is transmitted by means of the fowl tick Argas minia- 

 tus (persicus?}, most effectively when the tick is kept at a tempera- 

 ture of 30 to 35 C. In cold climates the disease is unknown. 

 Leishman and Hindle have studied very carefully the changes 

 which the spirochetes pass through in the body of the insect. 

 They found numerous exceedingly minute "coccoid bodies" in 

 the cells of the Malpighian tubules. These minute bodies are 

 considered 1 to be the products of a fragmentation of spirochetes 

 and to be capable of again growing into typical spirochetes. If 

 the view is correct these bodies necessarily play an important part 

 in the infection of the vertebrate host and in the inheritance of 

 the infection in the insect species. 



Spirochaeta Muris. This is a very short spirochete which 

 occurs naturally in a non-fatal relapsing fever of rats and mice. 

 It possesses one or sometimes two flagella on each end and multi- 

 plies by simple transverse fission. 



1 Nuttall: Harvey lecture, 1913. 



