408 PHYSIOLOGY. 



larva of Notonecta glauca, Cams considers that the globules of blood 

 are too small to be seen through the microscope, and that it is from 

 this cause that the motion of the juices is not to be detected in the 

 body. 



Among the Hemiptera, Wagener observed through the transparent 

 sides of the body of the young larva of Nepa cinerea distinct streams 

 of moving globules passing from the front backwards ; he could also 

 observe the pulsating dorsal vessel contracting in its chambers. In 

 the common bed bug (Cimex lectularius) I have perceived the pulsa- 

 tion of the dorsal vessel, and also an indistinct motion of fluids at the 

 sides of the abdomen. 



The remaining observations, chiefly compiled from Carus*, refer 

 chiefly to the circulation of the blood in insects not living in water. 

 Among the beetles, he observed it principally in the transparent 

 elytra and wings of Lampyris italica and splendidula, Melolontha 

 solstilialis and in a Dijticus ; then in the prothorax of Lam- 

 pyris splendidula. It here had the appearance of a strong current, 

 which came from the abdomen, and which, towards the end of the 

 pronotum, divided on each side into arms, that, upon each margin, 

 turned backwards. In the Orthopiera, on the contrary, he vainly 

 sought it in the wings, but Ehrenberg, according to the communication 

 of A. v. Humboidt, has seen a motion of the juices in a Mantis t. 

 The transparent wings of the Dic/yotoptera and Ncuroptera have 

 likewise here and there exhibited a motion of the juices, as well as the 

 wings of Libtllula depressa, Ephemera lutea, E. marginata, Hemerobius 

 chrysops, but most distinctly in Semblis bilineala and in the antennae 

 of Semblis viridifi. In the former, he saw the streaming blood pass 

 upon the anterior margin through the chief ribs, and distribute 

 itself upon the whole margin to the apex ; it returned back through 

 the ribs lying nearest to the posterior margin. Through the central 

 connecting transverse ribs, blood also passed from the proceeding to the 

 returning current. In the Hymenoptera, no motion of the juices was 

 perceived in the wings, and just as little in the Diptera$. In the 

 Lepidoptera, also, it still remains doubtful j but Carus thinks he may 



* Nova Acta Soc. n. c. C. L. vol. xv. Pt. 2, p. 1, &c. 



f Bericht iiber die Natur historischen Reisen der H. H. Ehrenberg und Hemprich. 

 Berlin. 1826. 4to. p. 22. 



\ In Eristalis tenax, Meig., and E. nemorum, M., I have recently observed blood pour 

 out of the roots of the wings during their motion, when the wing itself was cut off. 



