STRUCTURE OF THE BODY-LOUSE 19 



even into the hollows of the main hairs. In this 

 fluid are cells corresponding to the white corpuscles 

 of the blood of higher animals, but none corre- 

 sponding to the red corpuscles. This fluid is kept 

 circulating by means of an open contractile tube 

 which is, for convenience, called a "heart," and 

 which lies above the gut. Such an organ remains 

 to be described in the louse. The extensive con- 

 tractions of the gut mentioned above will aid 

 materially in the circulation of the coelomic 

 fluid. 



The internal organs of generation of the female 

 louse consist of a pair of ovaries, where the eggs 

 originate and grow, and a tube connecting these 

 with the exterior. Each ovary (Fig. 3, 23) is 

 made up of a bunch of five tubes which look like 

 strings of sausages in which each sausage is much 

 larger than the one in front of it. The swellings 

 which give them this appearance are due to the 

 growing eggs inside. The oldest egg is near the 

 base and the youngest one is near the tip in each 

 tube. As the eggs become fully developed they 

 pass one after the other (Fig. 3, 22) into the 

 central tube or oviduct (Fig. 3, 21). Here the 

 egg receives the mass of cement (Fig. 3, 20) 

 which surrounds its base when it is laid and fixes 

 it on to the hair or cloth to which it is attached. 

 The cement is poured into the oviduct from the 

 large glands (Fig. 3, 19) which secrete it. It is 

 probable that the eggs are fertilised while in the 

 oviduct, but there is a little gap in our knowledge 



