414 MICROBIOLOGY 



scription is as follows. "As it ordinarily appears, the organ- 

 ism measures from 2.5 to 7.8 ti in length, and it is made up of 

 from 4 to 13 nodes. The average length of the node in a great 

 many measurements is 0.6 /x, and the organism is 0.6 /x wide. 

 The nodes therefore are characteristically crowded and the un- 

 dulations steep. Compared with Sp. Obermeieri, Sp. refrin- 

 gens, and Sp. pallida, this form is much shorter, has more 

 crowded nodes and a greater diameter both relatively and ab- 

 solutely." 



The ends of Spirockaeta microgyrata Gaylordi are blunt 

 and rounded and there is no evidence of tapering at the ex- 

 tremities, nor of undulating membrane, nor of flagella. 



Treponema (Spirochaeta) muris. Wenyon 4 found in the 

 blood of a brown mouse affected with T. dimorphon very 

 active spirals. This spirochaete varies from 3 to 7 /u in -length 

 and about 0.2 /x in width. [They always appeared in the spiral 

 form. It produces a definite infection in mice with an incuba- 

 tion period of 5 to 6 days. An interesting fact was the dis- 

 covery of identical organisms in the lice which infested the 

 mice. It has not been cultivated. 



SPIROCHAETA AFFECTING MAN. 

 SPIROCHAETA OBERMEIERI. 



Place in nature. This organism, which bears the name 

 of its discoverer, was found by Obermeier in 1873 to be the 

 cause of relapsing fever. They appeared in the blood only and 

 were detected there during the fever, not during the intermis- 

 sions. 



Morphology. The spirochaeta of Obermeier is a delicate 

 spiral thread measuring from 7 to 9 /x in length (Novy), and 

 about 1.0 fjL in thickness. While this is its average size, it may, 

 according to some observers, be considerably longer than this, 

 its undulations varying from 4 to 10 or more in number. Com- 

 pared with the red blood cells among which they are seen, the 

 microorganisms may vary in length from one-half to 9 or 10 



4 Wenyon. The Jour, of Hygiene, Vol. VI (1906) p. 580. 



