MR. BOLTON ON THE UNITED SIAMESE TWINS. 
181 
To the ordinary touch there is not any middle line where the sense of feeling 
common to both the boys terminates ; but it is difficult to ascertain the pre- 
cise point where the inosculation of the one individual with the other takes 
place : and this is not discoverable by making punctures with a needle, for 
each boy shrinks from a puncture whenever it is made in any part of a vertical 
line drawn down the middle of the band. It is therefoie obvious, that the 
nerves of the common skin covering the band maintain a sensitive communi- 
cation with each of the two youths ; and it is reasonable to infer, that a similar 
communication subsists between the small arteries and veins, which mutually 
nourish the middle portion of the band. If, however, slight punctures be made 
at the distance of half an inch from the centre of the band, then the sensation 
is only felt by the individual belonging to the side punctured. 
From these evidences it may be concluded, that the united twins would be 
subject to certain distempers in common, although each possesses a distinct 
existence, and even different constitutional peculiarities. 
On the suggestion of Doctor Roget, a silver teaspoon was placed on the 
tongue of one of the twins, and a disk of zinc on the tongue of his brother : 
when the metals thus placed were brought into contact, the youths both cried 
out “ Sour, sour.” This experiment was repeated several times with the same 
result, and was reversed by exchanging the positions of the metals, when a 
similar effect was produced. 
These experiments prove that the galvanic influence passes from one indivi- 
dual to the other, through the band which connects their bodies, and thus 
establishes a galvanic circuit with the metals when these are brought into 
contact. 
They habitually face in one direction, and place themselves side by side, Eng 
to the right and Chang on the left, but are able to turn and remain in the oppo- 
site position. They always walk in the posture first described, although there is 
no other reason for this than established habit, as they are physically able to 
move in a reverse direction. Their united strength is great, for they can with 
perfect ease throw down a powerful man. At Philadelphia they also carried 
without inconvenience a person weighing rather more than twenty stone for 
a considerable distance. Their activity is remarkable ; they run with great 
swiftness, and elude pursuit so admirably, that in sportive exercises they can 
