In the spring of 1905 I was enabled to examine in the Pasteur Institute in Paris, the minute spiral thread (see Fig. 6) which has just been discovered and shown to be the cause of the most terrible and widely spread of human diseases, destroying the health and strength of those whom it does not kill and damaging the lives of their children, so that it has been justly said that this malady and the use of alcohol as a beverage are together responsible for more than half the disease and early death of the mature population of Europe. For more than thirty years, a few workers, here and there, have been searching for this parasite, and the means of suppressing the awful curse of which it is the instrument. It would have been discovered many years ago had greater value been set on the inquiries which lead to such discoveries by those who direct the public expenditure of civilized States. And now the complete suppression of this dire enemy of humanity is as plain and certain a piece of work to be at once accomplished as is the building of an ironclad. But it will not be done for many years because of the ignorance and unbelief of those who alone can act for the community in such matters. The discovery--the presentation to the eye and to exploring manipulation--of that well-nigh ultra-microscopic germ of death, seemed to me, as I gazed at its delicate shape, a thing of greater significance to mankind than the emendation of a Greek text or the determination of the exact degree of turpitude of a statesman of a bygone age. [Illustration: FIG. 6. The minute vibratile organism discovered by Fritz Schaudinn in 1905 in the eruptive formations and other diseased growths of syphilis--and called by him _Spirochæta pallida_ (since altered to _Spironema pallidum_): _a_, common phase; _b_, shortened and thickened form leading on to _e_ the Trypanosoma-like form; _c_, _d_, stages of division by fission; _f_, elongated multi-nuclear form; _g_, segments into which it breaks up; _h_, supposed conjugation of male and female units (after Krystallovitch and Siedlevski). This organism, though resembling the spirillar forms of Bacteria, is probably not one of that group of vegetable parasites, but allied to the minute animal parasites known as Trypanosomes (see pp. 145 and 181 and figures.) It is regarded as the ‘germ’ or active cause of the terrible disease known as Syphilis.]