THE VENEREAL DISEASES 81 



which causes syphihs have extended over a long 

 period, and not until very recently has any definite 

 conclusion been agreed upon. Through a series of 

 experiments by Schaudinn and Hoffman, which were 

 confirmed by Metchnikoff and others, it has been 

 decided that syphilis is due to a spirillum known as 

 Treponema pallidum, the reasons 

 for the long delay in arriving 

 at a decision being the fact that 

 the organism is exceedingly 

 difficult to stain, and, without 

 staining, it is almost impossible fig. le. — Treponema 



pallidum. 



to see it. 



For many years all efforts to cultivate Treponema 

 pallidum upon an artificial medium were unsuccess- 

 ful, although monkeys had been inoculated and from 

 the lesions other monkeys were successfully inocu- 

 lated, which seemed to be conclusive evidence that 

 Treponema pallidum undoubtedly caused syphilis. 

 Schereschewsky, a German bacteriologist, was the 

 first to bring about the growth of Treponema pal- 

 lidum on artificial media (1909). 



Syphilis is transmitted by sexual congress, may 

 be transmitted by a diseased parent, or may be 

 acquired by inoculation through an abrasion of the 

 skin or mucous membranes. 



