33. 

 SUMMARY 



A study haa bean made of the effects of various conditions of 

 hydrogen ion concentration, deficiency of oxygen and low temperature upon regen- 

 eration and metabolism in tadpoles of Rana olimata. 



These studies show that the optimum hydrogen ion concentration 

 for regeneration is neutrality or very near neutrality. As the hydrogen ion 

 concentration varies from neutrality in the direotlon of either aoidity or 

 bacisity, both the rate of regeneration and the total amount regenerated decrease, 

 at first gradually and then very rapidly. These effects are due to the hydrogen 

 and hydroxyl ions. 



The relative effect upon regeneration of any given hydrogen ion 

 concentration is practically the same for all stages of regeneration. 



In water of low oxygen content, both the rate of regeneration and 



the total amount regenerated are proportional to the oxygen present. Both the 



rate of regeneration and the amount regenerated decrease with a decrease of 



temperature. 



Tadpoles, whose regeneration has been completely checked by a 



decrease in temperature, retain the capacity to undergo a large degree of 

 regeneration to or beyond a psrlod at which control tadpoles have completed regen- 

 eration. Tadpoles, whose regeneration has been checked by insufficient oxygen, 

 •how this capacity to a lees degre3, while those whose regeneration has been 

 checked by acids or bases show it scarcely at all. It is suggested that this 

 may be due to a difference in the relative effects of the environmental factors 

 studied upon the phenomena of regeneration and differentiation. 



Carbon dioxide production of tadpoles in neutral water is propor- 

 tional to their weight. 



Carbon dioxide production is decreased by acids and increased 

 by bases. A high ra to of carbon dioxide production, when produoed by a basic 



