184 M. Jules Kunckel on the existence of 



Plate XIH. 



Fig. 1. Cytheridea spinulosa^ from left side. ] 



Fig. 2. The same, from above. (. v 40 



Fig. 3. The same, from below. f 



Fig. 4. The same, from front. ) 



Fig. 5. The same, hinge-margins. i v 84 



Fig. 6. The same, ventral contact margins, j 



Fig. 7. Cythere plana, left valve, from side. 



Fig. 8. The same, from above. 



Fig. 9. Pontocypris Davisoni, from left side. 



Fig. 10. The same, from below. 



Fig. 11. Loxbconcha Lilljehorgii, from left side. - x40. 



Fig. 12. The same, from above. 



Fig. 13. The same, from below. 



Fig. 14. The same, from front. 



Fig. 15. The same, from behind. 



XYII. — On the existence of Capillary Arterial Vessels in In- 

 sects. By Jules Kunckel*. 



Zoologists supposed that the circulation of the blood in insects 

 was limited to certain currents detected by Carus in transparent 

 larvae, when in 1847 M. Blanchard proved that the tracheae of 

 these animals fulfilled the function of arteries, by conveying, 

 in a peripheral space, the nutritive fluids to all the organs. 

 He ascertained, by means of delicate injections, the existence 

 of a free space between the two membranes composing the 

 tracheae : the injected fluid expelled the blood and replaced it. 

 After having verified and confirmed M. Blanchard's discovery, 

 M. Agassiz insisted upon the evidence of the demonstration. 

 Seeking afterwards to complete this discovery, he paid parti- 

 cular attention to the termination of the trachea?. In a memoir 

 published in 1849t, this naturalist distinguished the ordinary 

 tracheae terminating in little ampullae and the trachese termi- 

 nated by little tubes destitute of a spiral filament, which he 

 named the capillaries of the trachece. M. Agassiz expresses 

 himself as follows : — " In the grasshoppers which I injected 

 by the dorsal vessel I found in the legs the muscles elegantly 

 covered with dendritic tufts of these vessels (the capillaries of 

 the trachea) all injected with coloured matter ; and in a por- 

 tion of a muscle of the leg of an Acridium flavovittatum^ sub- 

 mitted to a high magnifying-power, I observed the distribution 

 of these little vessels, which has a striking resemblance to the 



• Translated from the ' Comptes Rendus,' July 27, 1868, tome Ixvii. 

 pp. 242-244. 



t Proc. American Association, 1849, pp. 140-143 j ti'anslated in Ann. 

 des Sci. Nat. 3« s^r. xv. pp. 358-362. 



