474 MEDICAL ENTOMOLOGY 



gently with a needle from behind forward the ovaries and a good deal of 

 the fat body can be made to extrude at the anterior opening, and can be 

 torn out. Having reduced the contents of the abdomen in this way, insert 

 the point of a sharp needle between the dorsal margins of the eighth and 

 ninth segments, and pull backwards, steadying the remainder by a needle 

 held on the anterior portion of the ventral margin. The last segments 

 can in this way be torn out with the rectum and hind-gut still attached. 

 To dissect out the salivary glands, place a rather blunt needle in the 

 antennal pit, piercing the head if necessary to get a good hold. Then 



insert a needle bent like a retractor in the space between 

 Salivary glands . . . . 



the metanotum and the first abdominal tergite, and 



pull the two apart by steady traction. The salivary glands will float out 

 in the saline as the segments are drawn away from one another, and can 

 be recognized by their glistening appearance. 



Mature ova are very easily obtained by making a slit in the abdominal 

 wall and compressing the body, when they are forced out. It is as well 



to do this in all dissections, even if they are not required, 

 The Ovaries , T r i 



as it leaves one more room to work. It the complete 



organ is required the only way to obtain it is to patiently chip away all 

 the tergites or sternites at the dorsal or ventral margin. It should be 

 remembered that the apical filaments of the ovaries are attached in the 

 dorsal and anterior part of the abdomen, and an effort should be made 

 to avoid tearing these attachments till the rest of the organ is free, or 

 they will spread out all over the slide. 



COLLECTION AND PRESERVATION .OF SPECIMENS 



Fleas can be most readily obtained from the animals on which they 

 feed, though failing this one can usually obtain them, either as larvae or 

 pupae, from the nests of the host. The latter is the most convenient 

 source in the case of the bird fleas. 



It is important to remember that all fleas will leave the body of the 

 host immediately it dies, and that therefore one has to be very quick in 

 collecting them from an animal which has been killed. With small 

 mammals captured alive it is generally easy, when they are plentiful, to 

 pick them off with a pair of forceps, or, if they are very small, with a 

 stiff brush moistened with water. A comb with fine teeth is also very 

 useful. Fleas are often confined to some particular part of the host's 

 skin, such as the rump, or the lower part of the abdomen, and a careful 

 search should be made before deciding that they are absent. In the case 

 of the more active fleas, and when there are only a few on each animal, 



