44 THE BIOLOGY OF THE FROG chap. 



which may spread over a considerable part of the body. 

 Necturus and other amphibians are Hable to attacks from 

 the same fungus. Eidam ^ has described a species of fungus, 

 Basidlobolus ranarufft^ which inhabits the ahmentary canal 

 of Rana esculenfa and R, oxyrhina. 



Times and Places of Breeding. — The breeding period 

 of frogs is in the early spring, soon after the animals have 

 emerged from their winter quarters. As in most amphibians, 

 the eggs are laid in the water, usually among the vege- 

 tation near the shore, and receive no attention from the 

 parents after they have been deposited. When the breeding 

 season is over, the frogs scatter and resume an active preda- 

 tory life. ■Skin exceptional cases, however, they have been 

 known to crawl back into the mud after the breeding season 

 is over, and resume for a time their winter sleep. AtDorpat, 

 Marquis observed that in one year Rana fusca, immediately 

 after the breeding season, crawled back into the mud and 

 remained two weeks before again emerging. 



The commencement of the breeding depends in a great 

 measure upon the temperature. The breeding of Rana 

 pipiens usually occurs, near Ann Arbor, in the latter half of 

 April or the first part of May. In general, a late spring 

 delays the time of breeding, and w'arm weather, on the other 

 hand, hastens it. Fischer-Sigwart, who for fourteen years 

 has carried on an extensive series of observations upon Ra7ia 

 fusca, found that the difference between the earliest and 

 the latest period was one month (from February 26 to 

 March 26) in Barmoosweiher, and one and a half months 

 (from February 26 to April 15) in Holdenweiher. The 

 breeding period depends to a certain extent upon local 

 conditions. In shallow ponds which are exposed to the 

 sun, and where consequently the water becomes warmed 



1 Eidam, " Cohn's Beilrage ziir Biologic der Pflanzen," Bd. 4, p. 181. 



