No. 510] THE AMERICAN TOAD 



741 



Another experiment, begun December 28, temperature 

 54° F., was made on five toads ranging between 3 and 

 7.5 cm. in length. These toads were put in a wire cage 

 filled with leaves and then buried in leaves, which had 

 drifted into an angle of a building. March 13, the cage 

 was examined and all the toads found dead. These toads 

 during this time had been subjected to several days of 

 0° F., weather. 



On March 28 I examined a drift of leaves. Two dead 

 toads were discovered half buried in the ground beneath 

 leaves. There were about eight inches of leaves over 

 them. 



Contrary to these observations are those Kirkland, 

 which might lead one to infer that toads can pass the 

 winter successfully under leaves in this region. But as 

 Mr. Kirkland 's observations were made in March, and 

 as toads in favorable springs emerge from their winter 

 quarters in this month, we are inclined to believe that 

 those he found under leaves had previously come out of 

 hibernation and had taken temporary refuge where he 

 found them. 



The sewers of a town constitute a most destructive trap 

 for toads. Sewer cleaners tell me that they take out 

 "piles of toads" especially in the fall and spring. Exam- 

 ination of the "man holes" in May shows that there are 

 on an average four toads in each one. At this rate, for 

 Worcester alone, there are no less than 24,000 toads thus 

 caught, which probably means their death also. It is mak- 

 ing a low estimate to say that 50,000 toads perish annually 

 in the sewers of Worcester. It is very probable that more 

 adult toads in a city are killed by this means, alone, than 

 by all others combined. 



I give the following table as a rough estimate of the part 

 that each known factor plays in holding the species in 

 check. 



Percentage of destruction until time of metamorphosis 

 caused by: 



