It is thus certain that the poison is inevitably absorbed in a very short time after contagion; consequently, it is utterly useless to attempt to prevent general infection when the venereal ulcers are already in development. Several of the witnesses before the Venereal Committee, 1865, stated the ill success of their attempts in this direction.

SUMMARY.

The causes of syphilis are predisposing and exciting. Predisposing causes are conditions facilitating the spread or increasing the severity of the disease. Syphilis is more severe in cold than in temperate climates and in hot ones for natives of cooler climates. Any cause which enfeebles the condition of the individual, increases the severity of syphilis, among which are starvation, drunkenness, &c. All races are subject to the disease: when it invades a district not previously accustomed to it, its course, like that of other contagious diseases, becomes for a time more severe. Probably individuals exist who are insusceptible to syphilis, and escape contagion of that disease as they escape contagion of small-pox, &c.

The sole exciting cause of syphilis is a subtle principle called the virus. It must be passed from the infected to the non-infected. It is non-volatile, easily destroyed by altering the chemical constitution of its vehicle, by acting on it with heat or acids. The poison almost always enters at a breach of surface: experience is against its absorption through unabraded surfaces.

The vehicles of the virus are-The secretions of all early syphilitic eruptions and the blood; but they usually cease to be contagious when the disease is almost extinct, and only the so-called tertiary affections are left. It is unknown if the saliva, milk, or semen, unless mixed with syphilitic secretions, convey the disease.

The secretions of co-existing diseases in syphilitic persons may be also contagious; certainly the disease is often transferred when vaccine lymph, matter of soft chancre, or vaginal discharges, are inoculated.

Close contact between individuals is eminently favourable though not necessary for communicating the disease; hence sexual intercourse, kissing, and suckling, are the usual modes of immediate contagion; while passing of spoons, cups, or glass-blowers' tubes, from mouth to mouth, and vaccination, are modes of mediate contagion.

There is probably no appreciable interval between the application of the virus to a denuded surface and its absorption; hence washing, or cauterisations, after contagion, in the hope of preventing the disease are useless, because the mischief they should prevent is already done.

Contagion by inheritance.-Our knowledge is imperfect respecting the ways in which syphilis is transmitted from parent to child. There is no doubt that if the mother is infected before or at conception, the child is very likely to receive the disease. Probably the child may contract the disease, if the mother is infected in the early months of pregnancy. If she is infected after the seventh month the child often escapes. As the disease subsides in the mother, the chances of escape for the child greatly increase, and after the second or third year of the mother's infection the child commonly escapes.

Infection from the father.-There is no doubt that the child may receive the disease from the father if the mother is also attacked. It is believed, also, that the child may inherit the disease from the father, while the mother escapes; but this is not established beyond doubt. It is supposed that the mother may become infected from the foetus; the evidence is much against the truth of that hypothesis.

SYPHILIS.

CHAPTER III.

PROGRESS OF THE DISEASE.

Incubation-The Initial Manifestation.

Incubation. The consequences of contagion are not immediately manifested. The time that intervenes between inoculation and activity of the poison is called the incubation period. It may be employed in three ways:-First. When the vehicle containing the virus is of a non-irritating character, the broken surface heals, and all trace of the inoculation disappears until the incubation is completed. Bärensprung's and Pellizari's cases of artificial inoculation are instances of this kind. Secondly. As the vehicle of the virus is often pus or discharge of an irritable kind, inflammatory action at the point of inoculation takes place immediately. This irritation subsides in a short time, and the part then remains quiet until the incubation is complete, when the syphilitic poison betrays its presence by characteristic phenomena. Vidal1 relates an instance of this: he inoculated the matter of a pustular eruption on the arm of a medical student, which produced a pustule in a couple of days; this healed completely in about a fortnight, and the experiment was supposed to have failed until the thirty-fifth day; action then recommenced by the development of a papule, which subsequently ulcerated, and general syphilis

1 Casenave's Annales des Mal. de la Peau et de Syph., p. 115, 1850, 1851; Vidal's Maladies Vénériennes, 1855.

followed in due course. Thirdly. If the syphilitic virus be carried in the pus of a contagious chancre, the time of incubation is occupied by the course of a chancre, which may or may not be concluded when the syphilitic poison begins reaction. This mode of beginning is perhaps almost as common as inoculation without the irritant matter of chancre, but the two diseased actions have no connection with each other, and are only accidentally co-existent.

1

The existence of a period of quiescence, first indicated by Cazenave, but obvious in some of the cases narrated by John Hunter in his "Treatise on the Venereal Disease," though he did not suppose it to be a necessary phenomenon, has been incontestably demonstrated sufficiently often by experimental inoculation for us to estimate its average length. The following series of artificial inoculations show the length of the incubation under these circumstances: they are selected instead of cases of accidental contagion, because, unlike the latter, there is no possibility of mistaking the time of contagion. Cases of accidental contagion tally in this point in every respect with those where the poison has been experimentally inoculated.

The cases in the adjoining table include all the trustworthy reports of experimental inoculation I have been able to procure. They number thirty-nine cases, of which the incubation is stated with exactness in thirty-six. In these the average delay before the poison became active was twenty-four days. The most common periods were twenty-five and twenty-eight days, and the extremes ten and forty-six days. In a case of accidental contagion, Rollet 2 believes it to have been only nine days; this is the shortest yet recorded. An instance of extreme length is that of Aimè Martin, who relates a case where a chancre appeared

3

1 Casenave Traité des Syphilides, p. 144.

2 Pluralité des Maladies Vénériennes, p. 26.
3 Thèse de Paris, p. 28. 1863.

Paris, 1843.

TABLE OF THIRTY-NINE CASES OF EXPERIMENTAL INOCULATION OF SYPHILIS; showing the Source of the Contagious Vehicle, the Length of Time that elapsed between the Insertion of the Poison and the Appearance of the Initial Manifestation, and the Date of the Development of the General Eruptions.

3 Idem.

35

18

31

23

15

17

25

23

174

About 15 weeks

45 days

1 Annalen des Charité-Krankenhauses, Berlin, 1860. Bd. IX.

2 Alfred Fournier: L'Incubation de la Syphilis. Paris, 1865.

Gibert's Reports on Contagion of Secondary Syphilis. Bulletin de l'Academie de Médecine, p. 888. 9 Mai, 1859. 5 Lancet, vol. ii. 1837.

6 Präger Vierteljahreschrift, 1851. Annales des Maladies de la Peau, t. iii. p. 185.

7 Archives Générales de la Médecine, 1858; Verhandl. der Würzburger ärztl. Ges., Bd. i. S. 117. u. Bd. iii. S. 375.

8 Gazette Hebdomadaire, 1860; Thèses de Paris, 1859; Follin: Pathologie Externe, vol. i. p. 735. ? Rapports à l'Academie de Médecine. Bulletins 1859, 1860.

10 Lancereaux: Traité de la Syphilis, p. 620; Gazette Hebdomadaire, 1863, p. 349.

11 Casenave: Annales des Maladies de la Peau, et de la Syphilis, t. iv. p. 47.

12 Vidal, Maladies Vénériennes, 1853, p. 358: Cazenave, Annales des Maladies de la Peau, et de la Syphilis, 1851, 1852, p. 115.

13 Danielssen: Deutsche Klinik, 1858, p. 322. 14 Canstatt's Jahresbericht, 1856, vol. iv. p. 337. 15 Kussmaul: Untersuchungen über den Constitutionellen Mercurialismus und sein Verhältniss zur Constitutionellen Syphilis, von Adolph Kussmaul, Würzburg, 1861. 8. 30. 16 Die Lehren von Syphilitischen Contagium; Auspitz. Wien, 1866. S. 217.

17 Idem, S. 225.