in life, and it is hard to color or stain it with dyes.  Its spiral form and faint staining have led to its being called the Spirochaeta pallida.[4] It is best seen by the use of a special device, called a dark-field illuminator, which shows the germ, like a floating particle in a sunbeam, as a brilliant white spiral against a black background, floating and moving in the secretions taken from the sore in which it is found.  Some means of showing the germ should be in the hands of every physician, hospital, or dispensary which makes a claim to recognize and treat syphilis.

    [3] See frontispiece.

    [4] Pronounced spi-ro-kee’-ta.

+Syphilis a Concealed Disease.+—­Syphilis is not a grossly conspicuous figure in our every-day life, as leprosy was in the life of the Middle Ages, for example.  To the casually minded, therefore, it is not at all unreasonable to ask why there should be so much agitation about it when so little of it is in evidence.  It takes a good deal out of the graphic quality of the thing to say that most syphilis is concealed, that most syphilitics, during a long period of their disease, are socially presentable.  Of course, when we hear that they may serve lunch to us, collect our carfare, manicure our nails, dance with us most enchantingly, or eat at our tables, it seems a little more real, but still a little too much to believe.  Conviction seems to require that we see the damaged goods, the scars, the sores, the eaten bones, the hobbling cripples, the maimed, the halt, and the blind.  There is no accurate estimate of its prevalence based on a census, because, as will appear later, even an actual impulse to self-betrayal would not disclose 30 to 40 per cent of the victims of the disease.  Approximately this percentage would either have forgotten the trivial beginnings of it, or with the germs of it still in their brains or the walls of their arteries or other out-of-the-way corners of their bodies, would think themselves free of the disease—­long since “cured” and out of danger.

+How Much Syphilis is There?+—­Our entire lack of a tangible idea of how much syphilis there really is among us is, of course, due to the absence of any form of registration or reporting of the disease to authorities such as health officers, whose duty it is to collect such statistics, and forms the principal argument in favor of dealing with syphilis legally as a contagious disease.  Such conceptions of its prevalence as we have are based on individual opinions and data collected by men of large experience.

+Earlier Estimates of the Prevalence of Syphilis.+—­It is generally conceded that there is more syphilis among men than women, although it should not be forgotten that low figures in women may be due to some extent to the milder and less outspoken course of the disease in them.  Five times more syphilis in men than women conservatively summarizes our present conceptions.  The importance of distinguishing between syphilis