This disease is due to an infective agent, which is asserted to be a bacillus, discovered by Lustgarten. This bacillus has special reactions to staining agents, which will be more fully referred to in the section on Bacteriology. The disease occurs only in the human subject, being transmitted from one person to another by contact.

Section of a hard chancre of the lip at its marginal part.

Fig. 123. - Section of a hard chancre of the lip at its marginal part. The granulation tissue occupies the skin under the epidermis, x 75.

Primary Lesion

The contagium is usually applied to some part of the external generative organs. It may be applied, however, to some other part, as to the finger (in the case of a surgeon examining a part), to the lip (as in the case from which Fig. 123 is taken), to the eyelid or other external part. After a period of incubation, usually extending to three weeks or more, it begins to show signs of local action. This is in the form first of a papule or vesicle, which acquires a hard or indurated base, and so takes the characters of the Indurated or Hunterian chancre. This consists of a raised surface, whose base has a hard, almost cartilaginous feeling. Examined microscopically it is found that the true skin is entirely replaced by granulation tissue, which forms a bulky mass of round cells over which the epidermis may be continued or may be removed in some parts. This structure may be regarded as inflammatory, but it may also be regarded as a kind of tumour, and may be taken as the type of the syphilitic tumour.

In its less common seats it may very closely resemble another form of tumour. Thus a chancre of the lip may be mistaken for an epithelioma, and be excised under that impression. This actually occurred in the case from which Fig. 123 was taken.

The tissue, although like in structure to granulation tissue, does not readily form connective tissue, but remains long in the rudimentary condition, and when it disappears leaves comparatively little of a cicatrix. On the other hand, it sometimes becomes caseous, but this does not so readily occur in the primary lesion.

The virus is carried from the indurated chancre by the lymphatics, and lodges in the neighbouring lymphatic glands, where it again produces similar results, namely, a great production of ill-formed granulation tissue which has little tendency to develop into proper connective tissue, but readily undergoes an irregular caseous metamorphosis. The glands undergo a slow enlargement and become hard.

Secondary Lesions

These are due to the fact that the virus passes from its local seat into the blood. This it does after an interval of some weeks from the time of the primary lesion.

The virus probably reaches the blood directly from the primary chancre, as well as by the lymphatics, but a certain period of time is necessary before it reaches the blood in sufficient quantity to produce any effect. Lang distinguishes in syphilis two periods of incubation, a First incubation extending from the time of infection to the appearance of the primary lesion, and a Second incubation between the primary and the secondary lesions. The first incubation has, according to the statements in recorded cases, a minimum duration of ten days, a maximum of ' forty-two days, and an average of twenty-four days. The second incubation is Longer, having a minimum of eight to fourteen days, a maximum of one hundred and fifty-nine days, and an average of six to twelve weeks.

By some it is believed that the induration of the primary lesion is itself due to a constitutional infection, and they cite in proof of this the fact that auto-inoculation, from an indurated chancre, is rarely successful, that is to say, the person is already protected by the primary indurated chancre from the production of another chancre by inoculation. It is to be observed, however, that in all such cases the original chancre has the start Of the inoculation, and before the period of incubation of the inoculation has elapsed there may be time for the blood to have been saturated with the virus. It is admitted that auto-inoculation is possible when done early enough. It seems scarcely possible to explain the second incubation except on the supposition that the primary lesion is, at least relatively, a local manifestation.

When an agent exists in the blood in a finely divided state it will be carried to all parts of the body, and if it produces lesions they will probably be symmetrical, as the corresponding parts in each lateral half of the body are for the most part in similar circumstances, and are similarly affected by any agent acting equally on them. The existence of symmetrical lesions is presumptive evidence that a disease is due to something in the blood. In the secondary stage of syphilis then we have the virus in the blood, and the result is symmetrical lesions of the skin, mucous membranes, bones, etc.

These secondary lesions are inflammatory in character, and have generally a resemblance to those of ordinary inflammations. They are most frequent in the skin, and so we have syphilitic Roseola, Eczema, etc., but other parts may be affected, and we have syphilitic Periostitis, Pharyngitis, etc. It is a question to what extent inflammations occur in internal organs in this stage; according to Hutchinson they are more frequent than is generally supposed, but are rarely seen because persons seldom die in the secondary stage.

The secondary stage has been aptly compared with the eruptive stage of specific fevers, it is like a fever long drawn out. There is in both cases a virus in the blood, and in syphilis there is frequently elevation of temperature. The analogy between the rash of secondary syphilis and that of measles, scarlet fever, small-pox, etc., is also suggestive, the skin affections in both classes of cases being inflammatory. During this stage, then, the virus is active in the blood, and the blood and secretions are contagious. The person is also in the position of transmitting the disease to the offspring, the virus passing into the germ and sperm cells. The virus dies out of the blood spontaneously, just as in the specific fevers, and the various secondary lesions disappear, generally in six to eighteen months.

In this secondary stage it is not common to meet with tumours like the indurated chancre. They are characteristic rather of the next stage, and when they do occur in this stage they are small and accompanied by more pronounced inflammatory manifestations.

A certain approach to the formation of granulation tissue, however, is often seen in the skin and mucous membranes during the secondary stage in the form of mucous tubercles or flat condylomata. These are flat superficial elevations of the skin or mucous membranes, usually met with near the external organs of generation and the anus, or in the mouth and the pharynx.