Scientific Proceedings. 



125 



88 (231) 



A spirochete found in the blood of a wild rat. 

 By W. J. MACNEAL. 



[From the Bacteriological Laboratory of the University 

 of West Virginia^ 



Of thirty nine wild rats (Mus decnmanus) caught here at Mor- 

 gan town one has shown a minute actively motile spiral organism 

 in the blood. It is present in very small numbers and careful 

 search with high magnification is necessary to detect its presence. 

 In freshly drawn blood it appears as an elastic spiral rapidly dart- 

 ing about, as often with one end forward as the other, forth and 

 back, rotating on its long axis as it goes. The movement is 

 frequently too rapid for the eye to follow. The spiral turns 

 appear quite permanent. At times a lashing movement of the 

 whole body is seen but the organism straightens out quickly to 

 its former shape. When caught among blood cells it jostles them 

 about in a lively fashion, while it is itself invisible. This seems to be 

 due to these flexuous movements of the whole organism. Actual 

 contact of the spiral appears to be necessary before the blood 

 cells are moved, which suggests that flagella are absent or too 

 slender to make a visible impression on an erythrocyte. 1 The 

 organisms are difficult to measure in the living condition but the 

 greatest length observed is about 5 fx. Much shorter forms are 

 recognizable in the fresh preparation, though harder to see on 

 account of the more active movement. The refractive index of 

 the parasite is not very great. 



The parasite stains readily by the various modifications of the 

 Romanowsky stain, and very intensely by the rapid method which 

 I have recommended for clinical staining of Spirochceta pallida} 

 It takes a uniform deep violet red color. The measurement of a 

 number of individuals shows a marked variation in length, the 

 shortest forms, consisting of one and three quarters turns or nodes, 

 having a length of 1.75 « ; the longest, consisting of three and 



1 Since this communication was written a long slender whip-like process extend- 

 ing from each end of a spiral has been clearly demonstrated. These are interpreted 

 as locomotive organs. 



2 MacNeal: Journal Amer. Med. Assn., Feb. 16, 1907. 



