246 



COMPARATIVE PHYSIOLOGY. 



the heart consists of two chamhers, an auricle and a ventricle, 

 the latter being supplemented by an extension {bulbus arterio- 

 sus) pulsatile in certain species ; and an examination of the 



Fig. 210. 



Fig. 211. 



Fig. 210.— The arterial tmnks and their main branches in the frog (Sana esculenta). 

 1 X IJ. (Howes.) I, lingual vessel; c. c, common carotid artery; p.cu^ pulmo- 

 cataneous artery; c. gl, carotid gland; au', right auricle; au'\ left auricle; v, ven- 

 tricle; tr, a, truncus arteriosus; pul', pulmonary; Ig, left lung; ao, left aortic 

 arch; br, brachial; cUj cutaneous; d. ao, dorsal aorta; ca, cceliaco-mesenteric; 

 ck', ccfiliac; hv, hepatic vessels; ff, gastric: pc\ pancreas; m, mesenteric; sp, 

 splenic; du', duodenal; h, hiemorfnoidal; iV, ileal; hy, bypogastric; c. il, com- 

 mon iliac; re, renal; k, kidney; ^s, spermatic. 



Fig. ail.—Venoustrunksand theirmain branches in thefrog(fiarao««(»fento). 1 x li. 

 (Howes.) I, lingual vein; e.j, external jugular; in, innominate; i.j, internal jugu- 

 lar; 8. 8c, subscapular; pr, c, vena cava superior; s. v, sinus venosus; hp, hepatic; 

 Iv', right lobe of liver; Iv", left lobe of liver; pt. c, vena cava inferior; qv, ovarian; 

 d, I, dorso-lumbar; od, oviducal; r.p, renal-portal; fm, femoral; sc, sciatic; a, 

 femoro-sciatic anastomosis; pv', right pelvic; vb, vesical; ant, ab, anterior ab- 

 dominal; a'j abdominal-portal anastomosis; W, ileal; sp, splenic; dii', duodenal: 

 I. int, lieno-intestinal; g, gastric; p, portal; Ig", left lung; put, pulmonary; m. cu, 

 musculo-cutaneous; br, brachial. 



course of the circulation will show that the heart is throughout 

 venous, the blood being oxidized in the gills after leaving the 

 former. 



Among the amphibians, represented by the frog, there are 

 two auricles separated by an almost complete septum, and one 



