No. 516] 



THE AMERICAN TOAD 



of the egg until death by old age that the egg, larva or 

 toad is not subject to attack. I have found little evidence 

 of the eggs being eaten in the ponds. Crayfish confined 

 in the laboratory ate a few. Saprolegnnia destroy a small 

 per cent, of the eggs, not by attacking the fertile ones 

 directly, but by spreading from those that are decaying. 

 The gelatinous sheath which envelops the delicate eggs 

 is almost a perfect protection, but, as soon as the tadpoles 

 wriggle out of it, they are preyed upon by fish, newts, 

 crayfish, insects, and especially the predaceous aquatic 

 larvae of insects. 



I give the results of my feeding tests to show how de- 

 structive some of the enemies of the tadpoles are. 



The above tests, with the exception of nos. 2 and 9, 

 were made with tadpoles which were hatched from eggs 

 laid about April 28. Since the transformation of the 

 larvae of this early laying began the twenty-second of 

 June, it is seen that a portion of these tests were made 

 with tadpoles almost ready to abandon the water. Those 

 for no. 9 hatched on the twenty-fifth of June. No. 2 

 was fed for the first five days on tadpoles of the early 

 spawn and the rest of the time on those hatched June 

 25. Only one tadpole a day was destroyed by this nymph 

 during the first five days. 



In treating the above data it must be taken into con- 

 sideration that these tests were made in the laboratory 

 and that tadpoles constituted the whole of the food of 

 these animals during the tests. This is a very abnormal 

 condition compared with that found in nature. 



