20. 

 H 2?-°4 snJ H3PO4. 7b8 sotted lines represent the aetual exp*rim*ntai data, tho 



•olid lin^a the theoretlcnl curve. Excepting in the cnce of H3PO4, these linee 

 eoineile vary closely. 



A comparison of the curves lor HHO3, H6r and H 3 S0 4 with the curves 

 for cirbon dio«ide production in bases (Fig. 9) for oxygen consumption In 

 bMM (Flft. 10) an! for regeneration in bases (Fig. 7) shows that they *re all 

 si'ailtr. Thess curves are also similar to ths metabolism cunrss drawn by 

 Powere (1919 b) from the data of Loeb and Kiss Hymen for oxygon consumption 

 in increasing amounts of anaesthetics. On the other hand, th-sy are ths 



opposite of ths cunrss of Kro&h (1914 a and b) for Increase in ths rate of 

 dsvslopment at increased temperatures, ths toxicity curves of Powers (1918 b) 

 for ths decrease In length of life with increase in concentration of toxlo 

 substances and of the curve tir torn increase in regeneration in increasing amounts 

 of oxygon (F1&. 38) to be discuss at later. This would suggest th«t whether 



criterion ohoaan be tine required to complete a given stage in development 

 (Krogh 1914 a and b), time required to ra^nerate a given p«r cent of the 

 amount removed, length of life (Powers 1913 a), or rata of oxygen metabolism, the 

 sffsot of temperature (Krogh 1914 a and b) hydrogen ion concent rati on, 

 insufficient oxygen >ni toxic substances (Powers 1918 b) follows ths same general 

 laws. That th**e various functions, - development, oxygen metabolism, regener- 

 ation, ems length of life - vary independently and bear no cattail relations 

 toward ona another is shorn by ths facts that an animal may be killed before it 

 has begun to regenerate in a ctadiut in which another may survive and undergo 

 conaiierable regeneration, while a marked change of 00 3 production may be pro- 

 duced by 1 medium which has apparently no effect upon regeneration. This 

 would indlests tamt tne threshold of toxicity of any given environmental agent, 

 as well as the velocity at which it booomej toxic # variea for the different 

 functions of the organism. However, that any environmental factor which 



