PARASITES OF ANIMALS. ‘ 3T 
small piece of gutta-percha into the back of an India-rubber 
shoe ; as, however, the chitine is not very elastic, this band is 
rather thinner in the middle, in order that it may bend and 
- fold a little when the skin is not extended by the lower lip. 
The latter consists, as usual, of two hard lateral pieces, of 
‘which the fore ends are united by a membrane so that they 
form a tube, of which the interior covering is a continuation 
of the elastic membrane in the top of the head; inside its 
orifice there are a number of small hooks, which assume 
different positions according to the degree of protrusion; if 
this is at its highest point the orifice is turned inside out, like 
a collar, whereby the small hooks are directed backward, so 
that they can serve as barbs. These are the movements 
which the ‘animal executes after having first inserted the 
labium through a sweat-pore. When the hooks have got a 
firm hold, the first pair of sete (the real mandibles trans- 
formed) are protruded; these are, towards their points, united 
by a membrane so as to form a closed tube, from which, 
again, is exserted the second pair of setz, or maxille, which 
in the same manner are transformed into a tube ending in 
four small lobes placed crosswise. It follows that when the 
whole instrument is exserted, we perceive a long membranous 
flexible tube hanging down from the labium, and along the 
walls of this tube the setiform mandibles and maxillz in the 
shape of long narrow bands of chitine. In this way thetube 
of suction can be made longer or shorter as required, and 
easily adjusted to the thickness of the skin in the particular 
place where the animal is sucking, whereby access to the 
capillary system is secured at any part of the body. It is 
apparent, from the whole structure of the instrument, that it 
- is by no means calculated for 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 feelers. As soon 
as the capillary system is reached, the blood will at once 
ascend into the narrow tube, after which the current is con-_ 
tinued with increasing rapidity by means of the pulsation of 
the pumping ventricle and the powerful peristaltic movement 
of the digestive tube.” 
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