144 



DEVELOPMENT OF THE FKOG 



At the time of hatching, the excretory organs thus consist on 

 each side of (1) a head kidney, which is a convoluted tuhe 

 lined by a glandular epithelium, and opening into the anterior 

 end of the body cavity by three ciliated openings, the nephro- 



FiG. 36.— A tailed frog, near the close of the metamorphosis, 

 dissected from the ventral surface to show the kidneys and repro- 

 ductive organs, x 4. 



A, dorsal aorta ; F, fat body ; GM, glomerulus ; KA, archinephric 

 or segmental duct; KM, Wolffian body; KP, head kidney, dis- 

 appearing; KU, ureter; O, mouth; OR, genital ridge; RV, tip of 

 ventricle ; TO, oesophagus, cut short. 



