116 



EXTERNAL FACTORS 



III.7 



peated weighings were made until a constant minimum was 

 reached. The results are set forth in the accompanying- table 

 and figure (Table XVI, Fig. 59). It will be seen that the 

 percentage of water rises very rapidly in the first fortnight, 

 from 56 % to 96 %, then decreases slightly, afterwards becoming 

 nearly constant. 



TABLE XVI 



Showing the rate of absorption of water by Tadpoles 

 (after Davenport). 



Days after hatching. Percentage of water. 



1 ... 56 



2 ... 59 

 5 ... 77 

 7 ... 89 

 9 ... 93 



14 ... 96 

 41 ... 90 

 84 88 



took 



60% 



Days 10 



SO 



FIG. 59. Curve showing change in percentage of water in Frog tad- 

 poles from the first to the eighty-fourth day after hatching. Abscissae, 

 days ; ordinates, percentages. (After Davenport, from Korschelt and 

 Heider.) 



A different, and a less satisfactory, method has been employed 

 by Loeb, hypertonic solutions being used to prevent the absorp- 

 tion of water. While the newly fertilized eggs of Fundulus 



