136 APPLIED IMMUNOLOGY 



agent has disappeared from the body, while the Was- 

 sermann " reagin " usually disappears very rapidly. 



In iriherited syphilis the Wassermann reaction is 

 positive in a very high percentage of cases, at least 90 

 per cent. The reaction tends to show moreover that a 

 great many congenital defects and maladies of young 

 infants, until recently regarded as due to syphilis, are 

 not caused by this disease. The Wassermann reaction 

 has thrown considerable light on the significance of 

 the laws of Colles and Prof eta. Colles' law is that the 

 mother of a syphilitic child may show no signs of 

 syphilis and is immune to the disease. It has been 

 found that in a very high percentage of such mothers 

 the blood gives a positive reaction. These cases proba- 

 bly have syphilis in a modified form, and therefore 

 cannot be reinfected. Prof etas law is that the chil- 

 dren of syphilitic mothers may be apparently healthy, 

 and yet not susceptible to syphilitic infection. A high 

 percentage of these children also give a positive Was- 

 sermann reaction, the explanation being the same as in 

 the case of Colles' law. 



Parasyphilitic A Sections, — Under this name are 

 grouped certain diseases of the nervous system, par- 

 ticularly paresis and tabes dorsalis. The discovery of 

 the Treponema pallidum in the lesions of paresis and 

 tabes has proved them to be true manifestations of 

 syphilis in the vast majority of cases. The Wasser- 



