ADAPTATIONS OF SURVIVAL VALUE 



twice the size of the first (very mvich like the majority in A). At least six 

 are very large, very active and feeding on the bottom mud. These compare 

 very favorably in size with others (much older) in Pool I) and they are fully 

 as large as those of the same clutch still in Pool F." ( It perhaps should be 

 noted that Pool F is the one in which growth rates were very rapid and the 

 size attained was very large in 1947. — Bragg, 1948). There was no social 

 activity. 



On the fourth day, sizes of tadpoles in B exceeded those ot the older 

 ones in Pool D now just entering metamorphosis but they were no larger 

 than their brothers and sisters still in Pool F. They were maintaining an 

 extremely fast growth rate. There was one exception. A single tadpole was 

 still small and inactive. In A, all tadpoles were still small but showed a slight 

 increase over the day before. All seemed healthy but they were maintaining 

 a slow growth rate. Water temperature in each aquarium ^24° C. 



On the fifth day, the contrast between A and B was even more striking. 

 Nine of the tadpoles in B were the largest of their species ever seen except 

 a few developing in Pool F in 1947. Up to this time no measurements had 

 been made for fear of disturbing the animals. Two from B were caught and 

 measured at this time. One = 28, the other = 37 mm. total length. 



Contrasts continued during ensuing days and on May 29 at 12:45 P.M. 

 the first one in B to develop forelegs was seen. This was on the seventeenth 

 day from hatching. Tadpoles in A were still small. 



On May 31, nineteen days from hatching, all the animals were measured 

 as follows: 



Three of the original ten were no longer present. None of the seven 

 remaining showed the slightest signs of metamorphosis. 



B. All ten were present. Nine had forelegs and the tenth had hind legs 

 well developed. Three had died because they could not leave the water when 

 ready to do so. It is to be noted that these were not eaten by their fellows. 

 There was no evidence of cannibalism in this culture at any time. All were 

 measured and then preserved for future study. The measurements were: 



(1) Body 11 Tail 9 mm. Total 20 mm. (tail shriveled) 



(2) " 13 " 8 " 21 



(3) " 12 " 7 " 19 



(4) " 11 "8 " 19 " reduced 



in 



