los Protection against Infectious Diseases. [Dec. 20, 



At the present time, however, we are able to go a step farther, and 

 say 



(1.) That a healthy woman become pregnant by a syphilitic man, 

 may give birth to a syphilitic child, and still remain healthy herself. 



(2.) That this woman suckling a syphilitic child is not exposed to 

 contagion from it. 



This singular immunity remains only to be explained, and we have 

 to determine whether it is not explicable, as one is led to think, by a 

 special kind of protection derived from the foetus. 



Several years ago it occurred to me as feasible to attempt the eluci- 

 dation of this proposition by means of some virus other than that of 

 syphilis, this disease having been found incapable of communication 

 to the lower animals. For this purpose none appeared to be more 

 suitable than that of anthrax, on account of the properties and life- 

 history of this organism being so well understood, and also by reason 

 of the very short period of time this disease takes to run its course to 

 a fatal termination after inoculation in most of the lower animals. 



The results of this investigation I propose giving in the following 

 pages : 



I. It is possible to directly inoculate a foetus in utero of a living 

 rabbit with an active growth of anthrax, without the bacillary disease 

 being communicated to the mother ; and further, the remaining 

 foetuses of this pregnancy under certain conditions have been found to 

 receive a like protection. A control animal subcutaneously inoculated 

 with the same growth died in sixty-eight hours. 



II. The mother may give birth to a litter of healthy young ones 

 some days later, with the exception of the one primarily inoculated 

 with anthrax, which is always dead when born. The longest period 

 of parturition after inoculation was ten days. 



III. The blood of the mother during the time intervening between 

 the inoculation of the foetus and parturition does not .reveal the pre- 

 sence of the anthrax bacillus when examined 



(i.) By fresh cover-glass preparations. 



(ii.) By aniline stained cover-glass preparations. 



(iii.) By cultivations, gelatine at 21 C., and agar-agar at 37 C. 



(iv.) By symptoms when animals were inoculated with it. 



IV. The mother subsequently inoculated with the blood of an 

 animal dead of anthrax, whose blood was swarming with the Bacillus 

 anthracis, does not succumb, but is found to have received protection. 

 The control animal died in forty-eight hours. 



V. Twenty-four hours after this second inoculation to' prove pro- 

 tection or otherwise, no anthrax bacilli were found in the blood of the 

 mother. Proved as in No. III. 



VI. The same animal, when re-inoculated with the anthrax blood 

 eight months later, was proved to be still protected. 



