C. Hay Murray 
281 
looking almost black with a chestnut coloured rim round them, this 
being due to their digestive juices turning the blood which they have 
absorbed into a very dense material almost like lamp-black. When 
the bug is found looking clear, and with little black in the ahmentary 
canal, it can at once be put down as not having had a meal for a 
long time. It seems to have a marvellous power of doing without food, 
having been kept by Westwood for twelve months sealed up in a bottle, 
and the writer has kept one, after a full meal, for over six months in 
a pill-box. It, however, makes full use of its opportunities when they 
offer, should the previous meal be digested. 
Messrs Howard and Clark of America, in their experiments on 
insect transmission of the virus of Poliomyelitis {Journ. Exper. Med. 
XVI. No. 6), kept the bed bug in captivity, and found that one meal 
must be digested ere the bug could be induced to take another, and 
“ hence four or five days to a week passed between successive feedings.” 
The “ feedings ” spoken of must have been meagre, as the -writer’s own 
experience is that, when the insect is allowed to reach repletion, the 
fasting intervals are lengthened to a great extent. In unoccupied 
houses there must be very long periods without food, and as the 
creature is usually found hiding in cracks and crevices to escape the 
light, this may have started the not uncommon popular belief that 
it actually feeds on wood. At present we do not know what, if any¬ 
thing, it feeds on when blood is not available. 
Macroscopically the bug is seen to be divided into two distinct parts, 
one, the smaller, comprising head and pro-thorax, while the other 
and larger part, includes meso- and meta-thorax and abdomen. The 
meta-thorax, however, is not visible from above, being covered by 
the rudiments of the front pair of wings which persist as two small 
scales at the base of the abdomen. The head is closely surrounded 
by the pro-thorax, whose anterior lateral borders project almost as 
far forwards as the line of the eyes, so that the head appears as if 
sunk in the thorax. The meso- and meta-thorax and the abdomen 
taken together form almost a circle, which in the male is distinctly 
pointed at the anal end, while in the female, the circumference is hardly 
broken at all. The general surface of the whole creature is covered 
with bristles which rise from cup-shaped depressions with perforated 
bases (Plate XXIII and Fig. 2). The bristle fits into the perforation, 
and muscles are attached to its base so that the bristles can be erected 
when occasion demands, as was once observed by the writer when one 
bug met another. Ordinarily, however, they lie pointing backward. 
Parasitology vn 
19 
