78 



Scientific Proceedings (126) 



and four-molar a 41 per cent. In all these cases there was an 

 increase in color value. This is probably due to an increase in 

 a brownish color component. There was some precipitation. 

 In many instances there was a finely divided sediment in the pi- 

 crate reduction mixture. For this reason a study was made as 

 to the effect of filtration. Ashless paper was used and in all 

 but very few cases filtration was followed by a decreased color 

 value. The error from such a cause ranged from 0.5 to 6 per 

 cent. A solution passed through six 9-cm. papers had a de- 

 crease in color value amounting to 17 per cent. 



38 (1SS8) 



Factors involved in the quantitative reduction of the tissues in 

 the stomach and intestine in amphibian larvae during 

 metamorphosis. 



By ALBERT KUNTZ. 



[From the Department of Anatomy, St. Louis University School 

 of Medicine, St. Louis, Mo.] 



According to data recorded elsewhere 1 , the following changes 

 in the digestive tube occur in Rana pipiens and Ambystoma 

 tigrinum during metamorphosis. 



Average reduction in length of stomach 

 and intestine 



Average reduction in weight of tissue 

 in stomach and intestine 



E. pi pi eps 



82.5 per cent. 

 56.5 per cent. 



A. tigrinum 



45.8 per cent. 



46.9 per cent. 



The role of autolysis and phagocytosis in the quantitative re- 

 duction of the tissues in the gills, fins, and tail of amphibian 

 larva? during metamorphosis has been studied repeatedly. Auto- 

 lysis and phagocytosis also account for a large part of the quan- 

 titative reduction in the tissues in the stomach and intestine. 

 The extrusion of tissue elements, especially from the mucosa 

 and submucosa, into the lumen of the stomach and intestine 



1 Kuntz, A., Anatomical and physiological changes in the digestive sys- 

 tem during metamorphosis in Rana pipiens and Ambystoma tigrinum. 

 Journal of Morphology (not yet published). 



