52 



SPIROCHETES 



Indeed, when we think of the many waj'^s in which syphihs 

 spirochaetes nia}^ be transmitted from person to person it is sur- 

 prising that the number of innocent cases is not much greater. 



The Spirochaetes. — The spirochsetes of syphihs, Spirochceta 

 pallida (Fig. 5C), vary in length from four to 14 ju (^oVir to -j-^V^y of 

 an inch) and are immeasurably slender. They are more closely 

 curled than the spirochaetes of relapsing fever, having usually 

 from six to 14 very regular, short, sharp curls, quite different from 

 the long graceful curves of a relapsing fever parasite. The 

 living organisms are very active and dart with great speed 

 across a slide, threading their way between blood corpuscles or 

 cells. The spiral turning of the body reminds one of the undulat- 

 ing movements of a swimming snake. Another spirochsete, Sp. 

 refringens (Fig. 5D), is often found associated with Sp. pallida. 



During the early stages 

 of their sojourn in the body 

 the spirochaetes can always 

 be found in the primary and 

 secondary lesions, and in the 

 neighboring lymph glands. 

 During the second phase 

 of the disease and also 

 toward the end of the 

 first phase the spirochaetes 

 occur in variable numbers 

 in the blood, and very 

 earl}^ make their way into 

 the cerebrospinal fluid in 

 the brain and spinal cord. 

 After it was found that 

 the spirochaetes actually 

 invade the central nervous system, and cause diseases of it, it was 

 supposed that this occurred only occasionally in late stages of 

 the disease. During the last year or two it has been shown, 

 however, that the great majority (80 per cent) of syphilitics show 

 distinct pathological changes in the spinal fluid, due to spiro- 

 chaetes in it, from the date of the primary sore, and are therefore 

 possible candidates for syphilis of the nervous system. During 

 the second phase the spirochaetes make a general invasion of 

 the entire body, later showing some special predilection for 



Fio. 8. Spirochceta pallida in liver tissue 

 of a congenital syphilitic. 



