CERTAIN PARASITIC INSECTS. 81 
suction can be made longer or shorter as required, and easily adjusted to 
the thickness of the skin in the particular place where the animalis 
sucking, whereby access to the capillary system is secured at any pue of 
the body. It is apparent, aue the whole struct- Fig. 14.* 
ure of the instrument, that it is by no means cal- f 
culated on being used as a sting, but is rather to 
be compared to a delicate elastic probe, in the use 
of which the terminal lobes probably serve as feel- 
ers. As soon as the capillary system is reached, 
the blood wi at once ascend into the narrow 
pidity 
the pumping ventricle and the Saa erful peristaltic 
movement of the digestive t 
If we compare the Hin of the louse 
(Fig. 15, Pediculus capitis, the head louse ; 
Fig. 15. Fig. 16, P. vestimenti, the body 
Y louse) with the young bed- 
bug as figured by Westwood 
(Modern Classification of In- 
sects, ii, p. 475) we shall see 
a very close resemblance, the 
head of the young Cimex be- 
ing proportionally larger than 
Head Louse. in the adult, while the thorax 
is smaller, and the abdomen is more ovate, 
less rounded ; moreover the body is white 
and partially transparent. The beak of 
the bed-bug we have studied from some 
admirable preparations made by Mr. E. 
Bicknell for the Museum of the Peabody 
Academy. 
Under a high power of the microscope  atonth of the Louse. 
specimens treated with diluted potash show that the man- 
* Figure 14 represents the parts of the — in a large specimen of Pediculus vesti- 
menti, entirely protruding, and seen from above, magnified one abies and sixty 
times; aa, the summit of en head, with fou er on each side; bb, the chitinous 
band, and c, the hind part of the lower lip — such as the appear through the s y 
strong transm ; dd, t os ding part of t lip (the haus- 
tellum); ee. the hooks turned outwards; f, the inner tube of suction, slightly bent and 
twisted; the two pairs of jaws are perceived on the outside as thin lines; a few bl 
globules are seen in the interior of the tube. 
