smcr» or the hydrogen io?; cokcehtratioe aei? oxtoe* 



COKTEITT OF f ATER UPOK RE0ISERATI01I 

 AWD METABOLISM IK TADPOLES 



IRTRODUCTIOW 



The direct influenoo of toapsraturn upon the rate of development 

 has Ions 8 * 6n recognised end hoe recent iy receive J considerable sttsr.tion, 

 espeeiil'y from the economic entonologlats who are working upon the relation of 

 wenthor conditions to the titan of emergence of insect pest*. Thit other 



environmental factors way eiwllnrly sifMi development la elso recognised 

 but ae yat the liter ture is ate age r. 



Probably no single environmental factor is of greater importance 

 to aquatic mVrniff than the chemical reaction (hydrogen ion concentrHio 

 of the water. Shelf ord and Powers (1915) have shown that marine fiehee 

 are extremaly eeneitlve to slight variations in the hydrogen ion concentration 

 of the water, onj Well* (1915) h*» shewn the sane to be true of freeh water 



fishes. 



The first study of tne effect of hydrogen ion concentration 



upon the rate of developoent is that of Loeb (1898). He compared the 



develcpsmnt of eggs of the sea urchin in normal sea water with those in 

 ssa eater to which 2 c.c. /lO WaOH per 100 c.c. had been added. At first 

 no difference was noted but after the thirty-t*o to sixty -four cell stages, 

 it wes evident the eggs in the alkaline solution hni developed no re rapidly. 

 The embryos in normal aater were still blestulao when those In the alkaline 

 water sere plutei, and st the ond of forty-eight hours, though all «ere 

 plutei, the ones in alkaline *»ter were lerger and farther developed. One, two 



