OBSERVATIONS AND EXPERIMENTS ON EUGLENOIDINA. 165 



body and tail and in total length as the others. Every one of the 

 "normal" tadpoles was larger than any one of the "dwarfs." 



2. Length of Intestine. (Table I.) A high correlation between 

 body size and length of the intestine was found. In almost every 

 case the larger the body the longer was the intestine. The average 

 length of the intestine of tadpoles from the alga pond was less 

 than half that of the other tadpoles. 



TABLE I. 



MEASUREMENTS OF BODY, TAIL, INTESTINE AND RECTUM, IN MILLIMETERS, OF 

 TEN SPECIMENS EACH OF "DWARF" AND "NORMAL" TADPOLES OF 



Rana pipiens. 



3. Length of Rectum. (Table I.) The rectum of the tadpole 

 is coiled in such a way that exact measurements are difficult to 

 make. Those in the table are only approximate, but they show 

 that in the "dwarfs" the rectum was only about half as long as 

 in the "normal" tadpoles. 



4. External Evidences of Metamorphosis. All of the "normal" 

 tadpoles exhibited rudiments of hind limbs. These measured 

 from 2.5 to 0.5 mm. in length. Only one of the "dwarfs" pos- 

 sessed rudiments of legs and these were only 0.25 mm. long. 

 The former had therefore progressed further in metamorphosis 

 than the "dwarfs." 



5. Internal Evidences of Metamorphosis. Shortening of the 

 intestine occurs during the metamorphosis of tadpoles. In 

 judging this character, however, one must take into account the 

 size of the tadpole. The shorter length of the intestine of the 

 "dwarf" tadpoles is probably due to the small size of the animal 

 rather than to a more advanced stage of metamorphosis. In 

 both groups of tadpoles the rectum was well differentiated. 



6. Character of the Contents of the Intestine. The intestines 



