In a general way it may be held that secretions of organs, or even of lesions, which are non-specific, are not contagious except as they happen to be mixed with blood or with disintegrated portions of actual syphilitic lesions; thus, for instance, vaccinal lymph might be safely taken from a syphilitic subject if there were absolutely no admixture of blood. _But the difficulty of securing pure lymph is such as to make its use inadvisable because of its danger._ _Suppuration frequently complicates syphilitic_ lesions. This is to be regarded as in the nature of a secondary and pyogenic infection. It has not been established that the germ of syphilis is by itself a pyogenic organism. _Gonorrhea or chancroid is often simultaneously contracted with syphilis_, with resulting clinical complications that are perplexing as well as difficult to treat. The contagion of chancroid acts promptly, as will be stated in the chapter on Chancroid; and so it may happen that the sore which begins as a chancroid is gradually converted into a true chancre, the change taking place so gradually that it is difficult to state when it begins or is completed. In this way result the so-called _mixed sores_, which may give rise to so much doubt that the surgeon feels it wise to wait for some secondary manifestations before deciding that syphilis has been acquired. Confusion is often created by preliminary treatment which the local lesion has received previous to its examination by the surgeon. Patients, especially in the lower walks of life, frequently go to a druggist or to someone who will cauterize the sore and thus mask its characteristics to a degree which makes prompt diagnosis impossible. Again, patients are often uncertain regarding the matter of time, which is of great importance; thus the sore which appears within a few days after exposure may be chancroidal, while one which comes on twenty or thirty days afterward may be syphilitic. These periods, however, afford little help when there have been repeated exposures, by which confusion may be caused; but an accurate and complete personal history will be helpful toward a correct diagnosis.