No. 515] 



THE AMERICAN TOAD 



(i.-r, 



thumb, or clasped by another male. This seems to be a 

 warning signal, for a male will release another as soon 

 as he chirps. In ponds males fight over a dead male as 

 though it were a female. They will clasp anything mov- 

 ing or which touches their breast that they can hold. 



It was mentioned above that spawn was deposited at 

 a depth of eighteen inches or more in certain ponds. This 

 depth appeared to be unusual, still the eggs developed 

 normally. The following experiment was made with 500 

 eggs to test the effect of depth on hatching. One hundred 

 eggs were placed in each of five tumblers over the tops 

 of which were stretched pieces of cheese cloth. These 

 tumblers were then attached six inches apart to a stick 

 which was fastened upright in pond no. 2. 



The experiment was started the twenty-first of May. 

 The eggs in the lowest vessel developed much faster than 

 those in the top, apparently as much as a day ahead. This 

 can probably be explained by the fact that a cold wave 

 came the clay the experiment was started and continued 

 for four or five days. Thus the surface was cooled more 

 than the deeper water, but the final result of the hatching 

 of the eggs at different depths was the same. A similar 

 experiment made in pond no. 4 gave uniform develop- 

 ment for eggs at depths between six and twenty-four 

 inches. From these data it is seen that depth to as much 

 as twenty-four inches does not affect materially the hatch- 

 ing of the eggs. 



Counts made on eggs in various places show that 68 

 per cent, to 90 per cent, are fertile. On an average, devel- 

 opment begins in 85 per cent, of the eggs. 



Development, Habits and Food 

 The toads leave the water as soon as they spawn. De- 

 velopment proceeds rapidly in the eggs from which tad- 

 poles emerge within two to six days, depending upon the 

 temperature. At this time the larva is about 3 mm. long 

 without mouth or appendages. On the under side of its 

 head behind the buccal area are two small crescent-like 

 depressions known as "sucking disks." These are 



