142 CONTEMPORARY SCIENCE 



organisms or spirochetae, so called since Schaudinn's dis- 

 covery in 1905 of the pallida, the microbic inciter of 

 syphilis. The search for the microbe of syphilis had been 

 unremitting since the early days of bacteriology, and not 

 a few false claimants held the field for a brief space. 

 Schaudinn's discovery was very soon confirmed, and has 

 now been firmly established ; and it is interesting to note 

 that in fact it was itself a confirmation of an observation 

 made a few years earlier by Metchnikoff and Bordet, who, 

 however, because of the technical difficulties of the quest 

 did not succeed in confirming their own findings. The 

 unusual difficulties surrounding the detection of the liv- 

 ing pallida in the body fluids, because of its extreme ten- 

 uity merely heighten the respect we must hold for the 

 zoologist Schaudinn's perspicacity. Very soon staining 

 methods were introduced to lighten the task of detecting 

 the pallida, but so capriciously did they act and so baffling 

 did the ordinary microscopic detection prove, that the 

 great promise of the employment of the pallida for pur- 

 poses of diagnosis and treatment was not at once 

 realized. 



None the less, a great advance in bacteriology had been 

 achieved, and a new class of microbes potentially disease- 

 producing was presented for study. Within a year a 

 second spirochete, called pertenuis, was discovered in the 

 lesions of yaws, a tropical disease having certain affinities 

 with syphilis. The search for the delicate spiral organisms 

 was not an easy one, and only the masters of bacteriologi- 

 cal technique were likely to succeed in it. Then suddenly 

 the labor was lightened and the road made smooth for a 

 rapidly succeeding succession of discoveries in this field 

 by the invention and application of the dark-field or ultra- 

 microscope. This instrument was perfected for observing 

 you are aware, operates by projecting powerful rays of 

 light in directions parallel to the surface of the micro- 

 scopic slide. Such a field if optically empty will be dark 

 and not luminous ; but if particles are present in it, the 



