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TEXT-BOOK OF ENTOMOLOGY 



The circulation of the blood in the wings directly after the exuvia- 

 tion of the nymph or pupa skin, and before they become dry, has 

 been proved by several observers. As stated by Newport, the so- 

 called " veins " or " nervures " of the wings consist of tracheae lying 

 in a hollow cavity, the peritracheal space being situated chiefly under 

 and on each side of the trachea. 



Newport gives the following summary of the observations of the early ob- 

 servers, to which we add the observations of Moseley. "A motion of the 



fluids has been seen by 

 Cams in wings of recently 

 developed Libellulidse, 

 Ephemera lutca and E. 

 marc/inata, and Chrysopa 

 perla ; among the Cole- 

 optera, in the elytra and 

 wings of Lampyris italica 

 and L. splendiditla, Me- 

 Inlontha solstitialis and 

 Dytiscus." Ehrenberg 

 saw it in Mantis, and 

 Wagner in the young of 

 Nepa cinerea and Cimex 

 lectu/arius. Carus de- 

 tected a circulation in 

 the pupal wings of some 

 Lepidoptera, and Bow- 

 erbank witnessed it in a 

 Noctuid (Phlogophora 

 metimlosa) ; Burmeister 

 observed it in Eristalis 

 tenax and E. nemontm, 

 and Mr. Tyrrel in Mttsca 

 domestica, but it has not 

 been observed in the 

 wings of Hymenoptera. 



Bowerbank observed 

 that in the lower wing 

 of Chrysopa perla the 

 blood passes from the 

 base of the wing along 

 the costal, post-costal, 

 and externo-medial veins, 



Fio. 382. Circulation of the blood in hind winfr of Peri- 

 jiliiiii'tn urii'iitiilix: tin- arrows indicate the usuiil direction of the 

 blood currents. After Moseley. 



outwards to tlie apex of 



the wing, giving off smaller currents in its course, and that it returns along 

 the anal vein to the thorax. He found that the larger veins, T 5 in. in diam- 

 eter, contained trachea; which only measured ^-.h^ of an inch in diameter ; 

 but in others the tracheSB^measured T .'. ri) , while the cavity measured only 5 ^ 

 of an inch. He states, also, that the trachea; very rarely give off brandies 

 while passing along the main veins, and that they lie along the canals in a 

 tortuous course. (Newport, art. Insecta, p. 980.) 



Bowerbank, also, in his observations on the circulation in the wings of Chry- 



