PARASITES AND DISEASE (VEGETABLE PARASITES) 179 



not as yet been isolated. Immunity is not established 

 by an attack; in fact, increased susceptibility seems to 



follow. 



SYPHILIS 



Definition. A specific infectious disease of slow evo- 

 lution, caused by the Treponema pallidum. 



Etiology. The cause of this disease has at last been 

 definitely proved to be the Treponema pallidum by the 

 inoculation of apes, which seem to be the only animal 

 besides man which is susceptible to the infection. 

 The infection occurs through minute abrasions of the 

 skin and mucous membranes, and is usually transmitted 

 by sexual intercourse. Innocent infection frequently 

 occurs in nurses and physicians from examining and 

 handling syphilitic patients, and in others through kiss- 

 ing, the use of drinking vessels, etc. 



Hereditary transmission is frequent, this being one 

 of the few diseases in which the direct transmission of 

 the disease from parent to offspring may occur. The 

 inheritance may come from either parent. A remarkable 

 fact concerning inherited syphilis is that referred to as 

 Colics' law, which is stated as follows : If a syphilitic child 

 be born of a healthy mother, the child cannot infect such 

 mother, though if it suckle a healthy wet-nurse the nurse 

 will become infected. The mother doubtless receives 

 immunity by way of the placenta without being herself 

 infected. 



Morbid Anatomy. The pathologic manifestations of 



