49 



COLLEGE ZOOLOGY 



The lymph spaces in the frog's body are very large. They 

 communicate with one another and with the veins. Four lymph 

 hearts, two near the third vertebra and two near the end of the 

 vertebral column, force the lymph by pulsations into the internal 

 jugular and transverse iliac veins. The lymph is colorless and 

 contains colorless corpuscles. 



The Excretory System (Fig. 416). A certain amount of sub- 

 stance resulting from the breaking down of living matter is 



FIG. 416. Urinogenital organs of the frog. A, male. i, fat body; 

 2, mesentery; 3, efferent ducts of testis; 4, ducts of seminal vesicle; 5, seminal 

 vesicle; 6, archinephric duct; 7, cloaca; 8, orifice of ureter; o, proctodeum ; 

 10, allantoic bladder; n, rectum; 12, kidney; 13, testis; 14, adrenal body. 



B, female, i, oesophagus; 2, mouth of oviduct; j, left lung; 4, fat body; 

 5, left ovary; 6, archinephric duct; 7, oviduct; 8, allantoic bladder; 9, cloaca; 

 10, aperture of oviduct; if, aperture of archinephric duct; 12, proctodeum; 

 13, mesentery; 14, kidney. (From Shipley and MacBride, after Howes.) 



excreted by the skin, liver, and intestinal walls, but most of it 

 is taken from the blood in the kidneys (Fig. 416, A, 12), passes 

 through the ureters (6), and then by way of the cloaca (7) into 



