VOL. LXX.] PHILOSOPHICAL TRANSACTIONS. 63] 



but rarely, that there is a pit in consequence of a chicken pock ; then ulceration 

 has taken place on the surface of the cutis, a common thing in sores. In the 

 present case, besides the leading circumstances mentioned in the case of the 

 mother, corresponding with the appearances on the child, and the external ap- 

 pearances themselves, we have in the fullest sense the tliird and real or principal 

 character of the small-pox, viz. the slough in every pustule ; from all which, I 

 think, we may conclude, that the child had caught the small-pox in the womb; 

 or at least a disease, the effects of which were similar to no other known disease. 



In opening the bodies of those who had either died of, or died while under 

 the small-pox, I always examined carefully to see whether any internal cavity, 

 such as the oesophagus, trachea, stomach, intestines, pleura, peritoneum, &c. 

 had eruptions on them or not, and never finding such in any of those cavities, I 

 began to suspect, that either the skin itself was the only part of the body sus- 

 ceptible of such a stimulus ; or that the skin was subject to some influence to 

 which the other parts of the body were not subject, and which made it alone 

 susceptible of the variolous stimulus. If from the first cause, I then concluded 

 it must be an original principle in the animal economy. If from the second, I 

 then suspected, that external exposure was the cause ; and I was the more led 

 into this idea, from finding that these eruptions often attack the mouth and 

 throat, two exposed parts ; add to which, that we generally find the eruptions 

 most on the exposed parts of the body, as the face, &c. 



With these ideas in my mind, I thought I saw the most favourable opportu- 

 nity of clearing up this point. I therefore very attentively examined most of the 

 internal cavities of this child ; such as the peritoneum, pleura, trachea, inside of 

 the oesophagus, stomach, intestines, &c. but observed nothing uncommon. I 

 have already observed, that in this child the face and extremities were the fullest, 

 similar to what happens in common ; from all which I may be allowed to draw 

 this conclusion, that the skin is the principal part which is susceptible of the 

 variolous stimulus, and is not affected by any external influence whatever. 



The communication of the small-pox to the child in the womb may be sup- 

 posed to happen in two ways ; one by infection from the mother, as is supposed 

 in the above case ; the other by the mother's having absorbed the small-pox 

 matter from some other person, and the matter being carried to the child from 

 the connection between the two, which we may suppose done with or without 

 first affecting the mother. 



Testimonies and opinions are various with respect to these two facts. Boer- 

 haave seems to have been led by his experience to think that such infection was 

 not communicable : for we find that he attended a lady, who having, in the 6th 

 month of her pregnancy, had the confluent small-pox, brought forth at the 

 regular period a child, who showed not the least vestige of his mother's disease. 



