600 PATHOGENIC MICROORGANISMS 



Wash in water, dehydrate in graded alcohols, and embed in paraflBn 

 by the usual technique. 



Examined after treatment by either of these methods, the spiro- 

 chsetes appear as black, untransparent bodies lying chiefly extracellu- 

 larly. They are characteristically massed about the blood-vessels of the 

 organs and only exceptionally seem to penetrate into the interior of 

 the parenchyma cells. 



Attempts at cultivating Spirochaeta paUida were at first unsuccessful. 

 Recently Schereschewsky ^ has reported that he has succeeded in ob- 

 taining multipUcation of the organisms on artificial media as 



follows : Sterile horse serum in centri- 

 fuge tubes was coagulated at 60° C. 

 until it assumed a jelly-like consist- 

 ency. It was then placed in the in- 

 cubator at 37.5° C. for three days be- 

 fore being used. The cultures were 

 planted by snipping off a small piece of 

 tissue from a .syphihtic lesion, dropping 

 it into such a tube, and causing it to 

 Fig. 130. — Spiroch^ta pal- sink to the bottom by means of centri- 

 LiDA. Spleen, congenital syphilis. fugalization. The tube was then tightly 

 (Levaditi method.) stoppered with a cork. In such an- 



aerobic serum cultures Schereschewsky 

 claims to have grown the organisms for several generations, though 

 not in pure culture. 



Miihlens also obtained growth of Spirochaeta pallida in horse serum 

 agar by a method which is very similar to that of Schereschewsky. 

 None of these observers, however, succeeded in carrying out Koch's 

 postulates with the cultures they obtained. This has recently been 

 done in the splendid investigations of Noguchi. Noguchi^ began his 

 work upon the Spirochaeta pallida in 1910 and 1911. His first success- 

 ful cultivations were made from the syphilis-infected testicles of 

 rabbits, and after many unsuccessful attempts, with slightly varying 

 media and technique, he finally succeeded in the following way: He 

 prepared tubes (20 cm. high and 1.5 cm. wide), containing 10 c.c. of a 

 serum-water made of diistilled water, three parts; and horse, sheep, or 

 rabbit serum, one part. These were sterilized by the fractional method 

 in the usual way (15 minutes each day). Into them was then placed a 



1 Schereschewsky, Deut. med. Woch., N. S., xix and xxix, 1909. 

 'Noguchi, Jour. Exp. Med., xiv, 1911; xvii, 1913. 



