Séaiicc du 17 Novembre 1920 \iC> 



the legs. An Kmpusa wliicli (liiriiii^a light has h)sl one 

 of its lore tibiae is Croni that (hile in danger of missing 

 its stroke and has, therefore, more diflienUy in feeding 

 itself. In this ease also its fale is little to he envied. It 

 is a slow wasting away, faihiie to monll properly and 

 iisnally death. 



IX. Peritracheal Circulation. Blanchard's Theory. 



Apail IVoni its imporlanee in the nnlolding of the 

 wings, the eirenlalion ol)s('r\e(l in the Ncins is of more 

 general interest. Let ns reeapitulate the observed 

 facts in a few words, l^aeh longilndinal ner\ ure contains 

 a narrow canal, lb«' Ivdchcn and another mneb widei' 

 ehaivnel, the /K-rilntchcdl .s/icaZ/j, in which the blood flows. 

 Although the transverse nervures do not contain ti"a- 

 cheae, they must be considered as prolongations of the 

 peritracheal sheath. 



The intrathoracic lacunae, in which the blood pres- 

 sure is increased, probably open into the wing system 

 so as to exerta thrust internally. 'J'he meso-and meta- 

 Ihoracic i)ulsating organs on the oilier hand exert a 

 suction which brings the blood back to the aorta from 

 the wing system. It is towards the end of the imaginai 

 iiioull that Ihe blood thrust - suddenly increased owing 

 to the contiactions of the body and also to the forced 

 acti\ity of the dorsal vessel and the pidsating organs — 

 acts on the wings and in full view of the oliserver brings 

 about their unfolding. 



These data lead us to make a comparison between 

 the anatomical fads observed in the Empusa and the 

 Iheorij of peritracheal circulation brought forward for 



