ANATOMY AND PHYSIOLOGY 



125 



ately under the integument. A simple tube in some larvae, it 

 consists in most adults chiefly of a series, of chambers, each of 



FIG. 159. 

 FIG. 158. 



Diagram of a portion of the heart of a dragon 

 fly nymph, Epitheca. o, ostium; v, valve; the ar- 

 rows indicate the course of the blood. After 

 KOLBE. 



FIG. 160. 



Dorsal vessel of beetle, 

 Lucanus. a, aorta; al, alary 

 muscle; o, ostium. After 



STRAUS-DiJRCKHEIM. 



Diagrammatic cross section of pericardial 

 region of a grasshopper, (Edipoda. a, alary 

 muscle; d, dorsal vessel; s, suspensory mus- 

 cles; sp, septum. After GRABER. 



FIG. 161. 



Blood corpuscles of a grasshopper, Stenobothrus. a-f, corpuscles covered with fat- 

 globules; g, corpuscle after treatment with glycerine, showing nucleus. After GRABER. 



which has on each side a valvular opening, or ostium (Fig. 

 159), which permits the ingress of blood but opposes its egress ; 



