REPRODUCTION AND DEVELOPMENT 



57 



length. How does it compare with the length of the intestine in the 

 adult? Is there anything in the feeding habits of frog and tadpole 

 which is correlated with the different lengths of the intestine in the 

 two? Examine the part of the digestive tract remaining within the 

 ccclom. Note, in addition to the parts above named, the liver with the 

 gall bladder between its lobes, and the pancreas lying in the angle 

 between the stomach and the intestine. Locate the lungs, kidneys, 

 fat-bodies, and the rudiments of the ovaries or testes. Draw the 

 above organs as they appear in position or slightly displaced to show 

 as much as possible, making an outline of the tadpole and its ccelomic 

 cavity about the organs. 



Exercise 65. — Transverse Sections. 



(f) With a sharp scalpel, cut transversely through the body in the 

 gill region and again at about the middle of the trunk. What is the 

 condition of the skeleton and of the nervous system in comparison with 

 those of the adult? If not clear, cut sections of a new specimen. 

 Draw a favorable section or sections, as directed by your instructor. 



Fig. 32. — Development of the frog. A, eggs. B, C, D, and E, cleavage, 



gastrula, and neural-fold stages. F, newlj' hatched tadpoles. G and H, later 



tadpole stages. /, J, and K, stages in metamorphosis to juvenile frog. 



H. Metamorphosis 

 Exercise 66. — Late Tadpoles and Juvenile Frogs, 

 (a) Examine several preserved specimens showing stages in the 



metamorphosis or change from the larval to the adult condition (c/. 



Fig. 32). These transformations occur while the tadpole is active and 



