THE SPIROCH^ETE OBERMETERI 495 



His observations were fully confirmed, and his views as to its 

 causal relationship to the disease have been established as 

 correct. 



Within recent years relapsing fever has been carefully studied 

 in different parts of the world, and the relationships of the 

 organisms have been the subject of much investigation and 

 discussion. This question will be referred to again below. 

 Recently also it has been shown that the so-called " tick fever " 

 prevalent in Africa is due to a spirochsete of closely similar 

 character, and results of the highest importance have been 

 established with regard to the part played by ticks in the 

 transmission of the disease. As a matter of convenience, we 

 shall give the chief facts regarding these diseases separately. 

 It has also been shown that spirillar diseases or " spirilloses," 

 as they are called, are widespread amongst vertebrates; they 

 have been described, for example, in geese by Sacharoff, in 

 fowls by Marchoux and Salimbeni, in oxen and sheep by 

 Theiler, and in bats by Nicolle and Comte, and it is interesting 

 to note that in the case of the spirilloses of oxen and fowls the 

 infection is transmissible by means of ticks. 



Characters of the Spirochaete. The organisms as seen in 

 the blood during the fever are delicate spiral filaments which 

 have a length of from two to six times the diameter of a red blood 

 corpuscle. They are, however, exceedingly thin, their thickness 

 being much less than that of the cholera spirillum. They show 

 several regular sharp curves or windings, of number varying 

 according to the length of the organisms, and their extremities are 

 finely pointed (Fig. 148). There are often to be seen in the 

 spirals, portions which are thinner and less deeply stained than 

 tlio rest, and which suggest the occurrence of transverse division. 

 They are actively motile, and may be seen moving quickly 

 across the microscopic field with a peculiar movement which 

 is partly twisting and partly undulatory, and disturbing the 

 blood corpuscles in their course. 



They stain with watery solutions of the basic aniline dyes, 

 though somewhat faintly, and are best coloured by the 

 Romanowsky method or one of its modifications. When thus 

 stained they usually have a uniform appearance throughout, or 

 may be slightly granular at places, but they show no division 

 into short segments. They lose the stain in Gram's method. 

 There is no evidence that they form spores. 



Novy found that the spirochaete of American relapsing fever 

 remained alive and virulent in defibrinated rats' blood for 

 forty days. He also succeeded, by Levaditi's method (p. 503), 



