TADPOLES AND FROGS. 185 
juice from the pancreas are poured upon it. Here 
further changes take place and the digested food is 
absorbed and taken to the blood-vessels. The un- 
digested portions of the food pass along the intestine 
to the cloaca, which is the common receptacle for use- 
Fic. 141.—Viscera of Frog. Si./n., small intestine; Z.Z, large intes- 
tine; Ur. B/., bladder; Ze.ca., pericardial cavity; V, ventricle; 7.4., 
large artery; Ao, aorta; ~, pulmonary artery; Px, pancreas. 
less substances from the food-tube, and the kidneys 
and eggs or sperm-cells from the reproductive organs. 
Thence the useless matter and the reproductive cells 
pass from the body. 
When the tadpole first comes from the egg, the food- 
tube quickly grows into the long coiled tube shown 
in Fig. 137 and this in turn gives place to the tube as 
we have seen it in the adult frog. 
It is interesting to note that the lungs, liver, and 
pancreas are outgrowths from the side of the food-tube, 
