754 CHRONIC INFECTIOUS DISEASES. 



virus, however, the system once contaminated by it obtains an immu- 

 nity almost absolute against subsequent infection. This very interest- 

 ing fact is analogous to the freedom from further attacks of scarlatina, 

 measles, and small-pox, enjoyed by persons who have once suffered 

 from those diseases. If we inoculate the discharge of a syphilitic sore, 

 or any other vehicle of syphilitic contagion, upon a person who has a 

 primary syphilitic induration or syphilitic ulcer, at the moment of in- 

 oculation, or who has already had one, we shall obtain negative results. 

 It is this fact which has given rise to such gross errors. For a long 

 time experimental inoculation was only practised upon individuals who 

 were already syphilitic, and, from the negative results which followed, 

 when blood or the secretion of secondary sores was employed, it was 

 inferred that blood and secondary secretions were not contagious. It 

 was not until it was determined to inoculate healthy, or, at least, non- 

 syphilitic persons with these vehicles that it was ascertained that the 

 want of result of the former experiment was simply due to the immunity 

 of syphilitic persons to further infection, and that their blood, and the 

 discharge from secondary syphilitic ulcers, were quite as infectious as 

 the secretion of a primary sore. Exceptions to this rule seemed to oc- 

 cur ; inoculation of the secretion of a primary sore upon the person 

 having the sore resulting sometimes in another sore. It is now deter- 

 mined that in such cases the syphilitic ulcer is complicated by the 

 chancre. The ulcer which follows the inoculation is a chancre, and 

 not a syphilitic ulcer. Contamination of the system with syphilitic 

 virus affords no protection against infection by the chancre, any more 

 than does the preexistence of one or several chancres secure the pa- 

 tient from further action of the chancrous virus. 



Since even a person having a primary syphilitic ulcer or induration, 

 but who has no secondary symptoms, is already secure from further 

 syphilitic infection, we may regard the primary induration and ulcer as 

 a sign of contamination of the system, and as the first symptom of con- 

 stitutional syphilis. Since, however, the above-named affections stand 

 first in the series of disorders which occur, and as the first sign of con- 

 stitutional infection always appears in the form of an ulcer or indura- 

 tion at the point of entry of the virus, the terms " primary induration '' 

 and "primary sore" may be regarded as perfectly appropriate. The 

 immunity against fresh infection, which contamination with syphilitic 

 poison affords, accounts for the interesting and formerly very perplex 

 ing fact that infants are infected by syphilitic nurses more frequently 

 than by syphilitic mothers. Generally, a child sucking at the breast 

 of its nurse is not at first syphilitic, and, therefore, is liable to infec- 

 tion, while the child which sucks the breast of a syphilitic mother is 

 nearly always syphilitic itself, and hence can not be inoculated. 



