s. 



regeneration of a port and tue metabolism of the animal ae a whole and whether 

 eubetances stimulating to oxygen metabolism are, ae Ihitley eu --osed, beneficial 

 to ths organism. In thle work the author hae been concerned only with the 

 extrinsic factors of regeneration. The intrinsic factors have bison considered 

 only ae they arose »s necessary corollaries to the work on environmental effects. 



Materials 



The tadpoles studied were larvae of Rana alimnta (Daw) collected 

 from a spring-fed marsh near !luncls, Illinois. Thres collecting trips ware made, 

 dated October 9, 1917, March 5th and 24th, 1918. This supply was supplemented 

 during t»e middle of the winter by a few tadpoles purchased fro* a local dealer. 

 All tadpoles were Identified by means of key to larval amphibia, fright (1914). 

 V' *. stock of tadpoles was kept in the greenhouse in an albarins tank supplied -rith 

 running wster to a depth of about 6 incft*s. Tha fosi supplied was f llano . "it ous 

 green alga*. All tadpoles were kept fasting luring experiments. 



Measurements of regeneration were Mfcdt by sain* of ■ caliper and 

 metal C.Q.S. ruler, obtained from Spencer Lense Company. The tail was the only 

 organ experimented upon. In making avers&ee there w*ss no elimination of 

 iniividuala, excepting in one or two instances, and tfeprc not? is made of the 

 fact tat the aberrant individual included in tne table. 



