500 



MINNA E. JEWELL 



carbon-dioxide production and oxygen consumption in bases, 

 and Powers' curve for oxygen consumption in increasing amounts 

 of anaesthetics had been drawn with the maximum concentration 

 used (that is, a concentration just sufficient to prevent regener- 

 ation or to cause the death of the organism) taken as the zero 

 of the ordinate instead of with the control, or absence of the 

 harmful factor, as zero all of the curves mentioned would be 

 somewhat similar. In all the theoretical zero falls far below the 

 actual zero. 



The final experiment of the oxygen series owes its value to an 

 accident. The tadpoles of this series were 71 to 76 mm. long and 



TABLE 7 

 Regeneration in low oxygen 



had rudimentary hind legs. No. 3 died without regeneration. 

 Of the other five, nos. 1 and 2, in 0.2 and 1.5 cc. O2 per liter, 

 respectively, showed marked retardation of regeneration when 

 measured on the twenty-first day (fig. 22). During the twenty- 

 second night the flow of water through the jars stopped, due 

 to clogging of the boiling apparatus by sediment from the water, 

 and before this could be remedied the water in the jars had be- 

 come well aerated. Since the tadpoles had been for two days 

 in aerated water, the original purpose of the experiment had to 

 be abandoned. An aerating jar with a rapid stream of air passing 

 through it was placed just after the mixing bottle so that the water 

 entered the first experiment jar aerated. Measurements made 



