2IO 



ESSENTIALS OF BACTERIOLOGY 



and likewise in the tertiary lesions, the very latest being the 



brain, and cerebrospinal fluid in cases of general paralysis, and 



establishing the identity of this disease with cerebral syphilis. 



Form. A minute, spiral-shaped organism, with 6 to 20 



curves, ends tapering. Actively motile in fresh specimen 



(Fig. 106), intracellular, and affecting glandular epithelium. 



Staining. The organism requires special staining, and a 



number of complicated methods have been introduced by 



different investigators. 

 The Giemsa stain is 

 said to give the best 

 results. (See Staining 

 Fluids, p. 47.) 



The slide is fixed, 

 dried in air, hardened 

 in absolute alcohol 

 twenty - five minutes, 

 stained with dilute 

 stain (i drop to i c.c. 

 of water) for ten min- 

 utes, washed in water, 

 and mounted. 



In tissues the organ- 

 Fig. 106 . Spirochaeta pallida. Micro- i sm can b e shown by 

 photograph made by Dr. R. E. Lavenson r , v i 



from a specimen prepared by H. Fox fixm g Wlth sllver m ~ 

 (Stengel). trate after the manner 



of Ramon y Cajal. The 



tissue is (i) Hardened in formalin for twenty-four hours 

 (the sections should be thin); (2) washed in water for one 

 hour; (3) alcohol, twenty-four hours; (4) i^ per cent, silver 

 nitrate solution in incubator at 37 C., three days; (5) washed 

 in water twenty minutes; (6) placed in mixture of pyrogallic 

 acid, 4 parts; formalin, 5 parts; distilled water, to make 100 

 parts, and kept in dark bottle for forty-eight hours; (7) 

 washed in water and alcohol and then embedded in paraffin 

 and sectioned. Spirochaetae black, tissues, pale yellow. Or 

 counterstain of fuchsin can be employed. 



