TREPONEMA PALLIDUM 261 



primary lesion appears two or three weeks after infection, first 

 as a papule which develops into an ulcer with a hardened base, 

 the so-called chancre, and at the same time there is a marked 

 swelling of the nearest lymph nodes. The symptoms subside and 

 six or seven weeks later secondary lesions appear as an eruption 

 on the skin and mucous membranes, accompanied by general 

 constitutional disturbances. In the tertiary stage masses of new 

 tissue, spoken of as gummata, are formed through the viscera and 

 in the periosteum. The organisms may usually be found in great 

 numbers in the primary sore and in the papules and mucous patches 

 which appear during the secondary stage. The latter fact explains 

 the infectiousness of the saliva. They have been found also in the 

 liver, spleen, and kidneys. In tertiary lesions they appear to be 

 much less numerous. As a sequelae to the tertiary stage, such 

 conditions as general paresis, arteriosclerosis, and locomotor ataxia 

 frequently result. Recently Noguchi and Moore have discovered 

 the spirochete in the brain of a certain number of paralytic insane 

 cases. 



Immunity. Immunity in syphilis appears to be somewhat 

 different to that produced in other infectious diseases. All at- 

 tempts to produce active immunity artificially have so far failed, 

 nor is passive immunity conferred by the injection of serum from 

 an animal in whom the disease has been produced. On the other 

 hand, man, as a rule, is not susceptible to reinfection during the 

 active stage of the disease. According to Colles's law a mother 

 who gives birth to a syphilitic infant may not herself contract 

 the disease, but may develop such a degree of immunity that she 

 can nurse the infant without becoming infected even though it 

 has venereal ulcers of the lips and tongue ; whereas the child would 

 infect the healthiest nurse even if she only handled and dressed 

 it. The converse condition is stated in Profeta's law ; namely, 

 an infant showing no taint but born of a syphilitic woman may 

 with impunity be suckled by its mother. Exceptions to both laws 

 have, however, been recorded. 



Microscopic Examination. Because of its low refractive index 

 T. pallidum is best seen with the dark-stage illumination. Material 



