62 THE FLEA [OH. 



be the stomach and intestine. The salivary glands 

 will be found at the side of the stomach with a certain 

 amount of fat round them. Their extraction is not 

 so difficult as might be supposed. The hooked needle 

 can be used to hook the salivary duct. 



The most difficult parts to dissect are the organs 

 connected with the mouth and rostrum. It is best 

 to remove the head and transfix it with the left-hand 

 needle, then to scalp the head by removing the dorsal 

 half of the chitinous carapace. A bold plunge with 

 the right-hand needle will sometimes effect what is 

 desired. A pull on the labium will sometimes bring 

 out the pharynx. It must be confessed that success- 

 ful dissections are often obtained more by good luck 

 than by skilful management. The use of dilute potash 

 solution facilitates the study of chitinous parts by 

 jellifying the muscles. 



CHAPTER V 



THE HUMAN FLEA AND OTHER SPECIES 



THE human flea (Pulex irritans) appears to 

 occupy an isolated position. The genus Pidex which 

 Linnseus established has now been reduced until it 

 contains one species only. The human flea belongs 

 to the group with eyes and without combs. In some 



