be retracted into the flexible membrane of the neck at i ts base. One other structure of interest in the cicada's head should be observed. This is a force pump connected with the duct (Fig. ?2"_, SalD) of the large salivary glands ?G/, GI) and used probably for injecting into the wound of the plant a secretion which perhaps softens the tissues of the latter as the bristles are inserted. Possibly the salira has ,'{lso a
Cl
GI
/VidB" /VixB"
FIG. 122. Median section of the head and beak of an aduIr cicada The sucking pump (Proie) is rhe mouth cavity, the collapsed roof of which (e) can be lifred like a piston by rhe large 'muscles (Pmp?Icls) arising on rhe clypeus (Clp). The liquid food ascends rhrough a channel between rhe maxillary brisrles (?IxB}, is drawn into rhe mourh opening (?Ith), and pumped back inro rhe pharynx (Phy), from which if goes inro rhe oesophagus (OE). A salivary pump (?alPmp) opens af rhe rip of rhe hypopharynx (Hp&v), dis- charging the secrerion of rhe large glands (GI, GI) inro rhe beak
digestive action on the food liquid. The salivary pump (SalPmp) lies behind the mouth, and its duct opens on the extreme tip of the tongue, where the salira can be driven into the charme} of the second bristles. .?lost sucking sects have two parallel channe]s between these bristles IFig. 9o), one for taking food, the other for ejectingsaliva, and the cicada probably bas two also, though in- vestigators diff-er as to whether there are two or on}y one.
[ 204]
THE
