c^ THE FROG. PHYLUM CHORDATA 



flattened, oblong, dark-red bodies which He one on each side in 

 the dorsal lymph sac above the coeiom and below the backbone. 

 Each consists of a mass of twisted uriniferous tubules, held 

 together by connective tissue and richly supplied with blood 



(PS. 



l^ illSO, 



ab.v. 



Fig. 294. — The urinary and generative organs of a male frog 



a.ab.v.. Anterior abdominal vein, cut short and turned back ; bl., urinary bladder ; cl., cloaca ; d.ao., dorsal 

 aorta ,f.b., base of fat body ■,f.b.v., vein of fat body ;f.v., femoral vein ; il.a., iliac artery ; i.v.c, inferior 

 vena cava ; k., kidney ; k.d., kidney duct ; mso., mesorchium ; oes., oesophagus ; pl.v., pelvic vein ; 

 r.p.v., renal portal vein ; r.v., renal veins ; sc.v., sciatic vein ; sr.b., adrenal body ; t.v., spermatic vein ; 

 v.eff., vasa efiferentia ; ves.sem., vesicula seminalis. The testes are not labelled, nor are the sciatic 

 plexuses, a portion of which may be seen beside the ihac arteries. 



A diagram of these organs will be found on p. 381. 



vessels. Each tubule begins blindly in the substance of the kidney 

 as a thin-walled Bowman's capsule, whose side is indented by 

 a cluster of blood vessels, the glomerulus, the rest of the tubule 

 being glandular. The glomeruli receive blood only from the renal 

 artery, the tubules also from the renal portal vein. The tubules 

 open into collecting tubes, which run across the kidney to enter 

 the main duct of the organ ; this, the Wolffian duct, should not 



