mOGS, TOAUS, AJJU SALAMANDERS 283 



latory system. It is composed of three principal parts, 

 the muscular ventricle and two thin-walled auricles. The 

 blood is sent out from the anterior end of the ventricle 

 through a single artery, which gi\'es off three branches on 

 each side. Four of these pass to (iifferent parts of the bodj' 

 and end in capiharies The capillaries unite to form veins 

 through which the l_ilood returns to the right auricle of the 

 heart. Of course this blood is impure and charged with 

 carbon dioxide. The remaining two branches carry blood 

 to the lungs and skin, where it is purified and returned to 

 the left auricle. The auricles erupt}- their Ijlood, iKjth pure 

 and impure, into the ventricle. But by a complicated 

 sj'stem of valves and bj' the manner in ■which the suigle 

 artery branches the two kinds of Ijlood mix l)ut little and 

 the purest blootl is sent to the head, the next best to the tlif- 

 ferent parts of the body, and the impure l)ack to the lungs. 



The food and method of obtaining it. — The frog feeds 

 upon living, moving animals only; as -worms, moths, flies, 

 beetles, etc. These are caught, while they are in motion, 

 on the end of the tongue as it is darted from the mouth with 

 great rapidity. The stick}', mucous secretion on the tongue 

 serves to hold the pre)-. The food is swallowed whole and 

 digested at leisure. 



Reproduction and Ufa history. — AMien mature, the eggs 

 are set free in the liody canity and finally find their way into 

 the mouths of the o^-iducts. In the passage through the 

 o-viduct each egg becomes coated with a gelatinous ma- 

 terial which swells greatly ^\'hen the egg reaches the water. 

 The eggs are deposited in large, irregular, jellylike masses, 

 usually near the edges of pools and verj- often about the 

 stem of some plant (Fig. 163). After a number of warm 

 days each egg hatches into a black, wiggling oljject with an 



