HUMAN PEDICULI 331 



gradual drinking in of the blood. Allowing it, therefore, 

 to attach itself once more, he sees "at the top of the 

 head, under the transparent skin, between and a little 

 in advance of the eyes, a triangular blood-red point 

 appear, which is in continual movement, expansion and 

 contraction alternating with increased rapidity. Soon 

 this pulsation becomes so rapid that several contractions 

 may be counted in a second." Swammerdam also had 

 noticed this, and likened the rapid movements of this 

 little pumping machine to the quick oscillation of the 

 balance-wheel of a watch. Schibdte continues, "The 

 whole digestive tube is now in the most lively peristaltic 

 movement, filling itself rapidly with blood, as is easily 

 observed ; the long oesophagus is particularly agitating, 

 throwing itself from one side to another inside the neck, 

 bending itself so violently as to remind one of the 

 coiling of a rope when being shipped on deck." 



The insect was now thoroughly hard at work, and 

 this was therefore the opportunity for the next stage in 

 the proceedings. In order to prevent the retraction of 

 the proboscis, which would have followed the withdrawal 

 of the insect, the experimenter determined to decapitate 

 it suddenly, hoping that thereby the proboscis might 

 remain extended. The forepart of the insect was there- 

 fore rapidly severed with a pair of fine scissors without 

 previously disturbing it in its feast. The decapitated 

 head, having been left as it was for a short time, was 

 then gently raised with forceps, and the proboscis 

 gradually withdrawn ; the whole was then transferred to 

 a slip of glass, and placed under the microscope without 

 pressure. The appearance presented was such as is 

 shown in the accompanying diagram (Fig. in). A 

 long fleshy tube was depending from the mouth ; at its 

 base was a stouter part, furnished at its apex with 



