No. 505] 



NOTES AND LITERATURE 



59 



veloping in a dish to account for the fact that in experiment 

 with eggs of 1.81 mm. and 1.20 mm. in diameter, the eggs of both 

 sizes developed equally fast. The less crowded condition, he 

 thought, compensated in that case for the small size of the eggs. 

 The question as to whether or not the initial size of the egg is 

 a determining factor in the rate of development seems to me, 

 therefore, still an open question. 



Next, Chambers investigated the influence of the size of the 

 eggs upon development at different temperatures. Eggs of B. 

 temporaries of the same size were reared separately under tem- 

 peratures ranging from 10° to 25° C. He found in this case 

 of E. temporaries, which spawns early in the spring, that both 

 large and small eggs develop at low temperatures, but only the 

 large eggs are capable of resisting higher temperatures. On the 

 contrary, in case of B. esculenta, which spawns in May and June, 

 all eggs develop well at high temperature (19°-27° C.) and only 

 the large eggs develop at low temperature (10°-12° C). 

 Chambers therefore concludes that large eggs are more efficient 

 in withstanding extremes of temperature. 



He found, furthermore, that when eggs of the same individual 

 are reared, under equal conditions of temperature, eggs larger 

 or slightly smaller than those of normal size (the size of the 

 majority of eggs is considered the normal size) develop to ad- 

 vanced stages, but the extremely small eggs invariably die out 

 while yet in the early stages of development. In a lot of eggs, 

 where the normal size was 1.5 mm. only 8 out of 23 eggs meas- 

 uring 1.15 mm. in diameter and none of those measuring 1.05 

 mm. reached an advanced stage. Chambers is strongly inclined 

 to think that there is a set limit to the size of the egg of a given 

 species, beyond which it can no longer vary without losing its 

 power of development. But the failure of abnormally small 

 eggs to develop can also be interpreted differently, since the 

 exceptionally small size may be due to the circumstance that the 

 eggs have not yet attained full maturity. 



Chambers states that large tadpoles develop always from large 

 eggs, and that the ratio between the volumes of different eggs 

 is maintained more or less constant during the early stages of 

 development, i. e., the tadpoles are in the same relation to each 

 other, as regards volume, as the eggs from which they have 

 developed. 



Regarding the cellular elements of the young developed from 



