TREPONEMA PALLIDUM 151 



Keep in this bath for 3 days at body temperature, excluding light and 

 changing the solution daily. 



6. Place in the following solution for 24 hours at room temperature: 



5 per cent, solution of formaldehyde, 50 cc. 

 Pyrogallic acid, i Gm. 



7. Wash in distilled water. 



8. Dehydrate in absolute alcohol. 



9. Clear in xylol. 



10. Imbed in paraffin. 



11. Section and mount. 



Treponema appear black. 



Growth. Cultivation of treponema pallidum on artificial media is difficult 

 and time-consuming; most attempts are futile and as yet this method of study 

 is not practical in diagnosis. 



Material taken from chancres and other open lesions containing treponema 

 also contains numerous other organisms and isolation of the treponema from 

 these is effected by inoculating the material into a rabbit's testicle. 



When the contaminating organisms die out and the treponema multiply, 

 media planted with an emulsion of such a testicle yield pure cultures. 



The treponema pallidum is an obligate anaerobic and has only been propa- 

 gated in ascitic broth and ascitic agar containing a piece of sterile rabbit 

 testicle. 



Stab cultures in deep tubes of agar, incubated at 37C., after several days, 

 show growth near the bottom of the tube which first appears as fine white lines 

 radiating from the stab. 



The character of lesion that develops following inoculation of a rabbit 

 depends upon the tissue in which the treponema are deposited. If deposited 

 in the subcutaneous tissue of the scrotum a chancre usually develops. If de- 

 posited deep in the testicular tissue gumma develop. The production of gumma 

 is desired when rabbits are inoculated as a primary step to procure pure cultures, 

 because the gumma are most apt to contain spirochaeta not associated with 

 other organisms. 



Resistance. Treponema pallidum is more susceptible to mercury and 

 salvarsan than to other chemical germicides. It does not form spores and 

 probably is destroyed by short exposure to moderate degrees of heat. 



The time it can remain alive and infectious on linen, glass, soap and other 

 objects, subject to contamination is undetermined; that it does survive for short 

 periods at least on such objects has been proved by infections contracted through 

 contact with them. 



Pathogenesis. Treponema pallidum occurs in man only. Conditions 

 similar to syphilis can be produced in monkeys and rabbits by inoculation. 

 Syphilis, like some other diseases, produces a hypersusceptibility of the skin to 

 irritants in general and especially to the infecting organism. In syphilis this 

 phenomenon is most marked in the tertiary period. Noguchi has attempted to 

 base a diagnostic test on this fact the test is not generally available on account 



