332 HAROLD CUMMINS 



Humidity as well played an important role in migration. The 

 lowest relative humidity accompanied by migratory activity 

 was 75 (table 1, May 7), The optimum humidity, however, 

 was much higher, ranging between 90 and 100. It is not sur- 

 prising to find a high humidity requirement in this group. From 

 the data at hand it is difficult to ascertain the relative importance 

 of temperature and humidity. Since in the cool period of April 

 the humidity was at times as high as that favoring migration in 

 warmer weather, and since migration temperatures were asso- 

 ciated with high humidities, the inference is that migration 

 necessitated a coincidence of favorable temperature and favorable 

 humidity. 



The duration of the migration period was much longer than 

 would be expected. The periods in 1914 for four species were as 

 follows: leopard frog, 43 days; wood frog, 33 days; swamp tree 

 frog, 35 days; spring peeper, 27 days. In other years these 

 periods might be shortened by more favorable weather condi- 

 tions or lengthened by adverse circumstances. If the cool 

 weather of April had not intervened, the periods in 1914 might 

 have been shortened considerably. Inasmuch as the frogs were 

 hibernating under variable conditions, it is conceivable that the 

 duration of warm weather necessary to arouse some of them 

 would be longer than the requirement of other frogs hibernating 

 in readily warmed localities. Further, in localities permitting 

 frogs to hibernate under similar conditions, perhaps the wave of 

 migration would have an early climax and be very short. In 

 support of the supposition that some frogs were aroused late, 

 only one type of concrete evidence can be offered here. As late 

 as April 27th there was taken in the trap an occasional leopard 

 frog with the flabby edoematous appearance of individuals fresh 

 from hibernation. We know nothing of the wanderings of frogs 

 en route to breeding ponds. Inasmuch as the references to this 

 point lead one to infer that the route is always a direct one and 

 probably continuous, the results of an experiment leading to 

 partially contradictory evidence is here recorded. On March 

 31st fourteen leopard frogs captured in the pond, two males and 

 twelve females, were each marked by a white string tied care- 



