Pathogenesis and Specificity 795 



A bit of the tissue should be emulsified in a mortar with citrate 

 solution and examined with a dark field illuminator to make 

 sure that the organisms to be cultivated are present. 



If they are found, and the material shown to be adapted 

 to cultivation, each of the remaining bits of tissue is taken up 

 by a thin blunt glass rod and pushed to the bottom of a cul- 

 ture-tube and into each tube several drops of the emulsion 

 examined are introduced by means of a capillary pipet, also 

 inserted deeply into the medium. The tubes are next incu- 

 bated at 37 C. for two or three weeks. In successful tubes, 

 in which the medium has not been broken up by gas-producing 

 bacteria, there is a dense opaque growth of bacteria along the 

 line of puncture, and a diffuse opalescence of the agar-agar 

 caused by the extension into it of the growing treponema. 

 A capillary tube cautiously inserted into the opalescent me- 

 dium withdraws a particle that can be examined with dark field 

 illuminator. When such observation shows the cause of the 

 opalescence to be, in fact, the treponema, the tube can be 

 cautiously broken at some appropriate part and the trans- 

 plantation made from the opalescent part of the medium to 

 fresh appropriate culture-media. By these means, after a few 

 trials, pure cultures of treponema were secured. 



The colonies were said never to be sharp, but always faintly 

 visible. There is no color and no odor. 



By inoculating the organisms recently secured from human 

 lesions (by the method given) into monkeys (Macacus rhesus 

 and Cereopithicus callitrichus) Noguchi was able to produce 

 typical syphilis of the monkey, thus showing that the virulence 

 of the organisms was not lost in the cultivation. 



Pathogenesis and Specificity. There can be no doubt 

 about the causal relation of Treponema pallidum to syphilis. 

 It is unknown in every other relation; it has appeared in 

 every required relation, and thus has completely fulfilled the 

 laws of specificity laid down by Koch. Treponema pallidum 

 is not only pathogenic for man, but, as has already been 

 shown, can also be successfully implanted into chimpanzees, 

 macaques, rabbits, guinea-pigs, and other experiment animals. 

 As syphilis is, however, unknown under natural conditions, 

 except in man, it may be looked upon as a human disease. 



The organism enters the body through a local breach of 

 continuity of the superficial tissues, except in experimental 

 and congenital infections, where it may immediately reach 

 the blood. 



