The Bullfrog, Rana catesbeiana Shaw. 81 



The breeding record extends from June 16 to July 10. Doubtless it 

 begins earlier some years or extends beyond July 10 in belated seasons. 

 On July 25, 1913, females were taken with ripe ova. An average of 

 breeding records gives June 28. 



THE EGG-LAYING PROCESS. 



The egg-laying process usually occurs at night, when the species 

 is most active. The bullfrog is a solitary form; yet at the height of 

 breeding a mill-pond may have a dozen or more pairs in it. Or some 

 lakes may be well enough supplied with them to furnish the famed 

 bullfrog choruses of June and July. Probably, as with other species 

 of Rana, when the process has really begun it takes but a very few 

 minutes. At first we thought this species did not always keep the 

 same position. Sometimes from the glutinous mass at or near the 

 surface narrow string-like pillars extended down a foot or more to lower 

 submerged branches. Then the strings were continued along the lower 

 branches for various distances. A string-like deposition also occurs 

 sometimes when the eggs are found on the finer roots of an overturned 

 stump in the water. These two sorts of observations led us to the 

 inference that the female did sometimes move during the deposition. 

 The pancake-like film (Plate i, Fig. 2s) has, however, been recorded 5 

 or 6 times as frequently as the string-like deposition. Furthermore, it 

 is our belief that the film is the usual method of ovulation, as it is in the 

 bullfrog's nearest relative, the green-frog ; and that the string-like deposi- 

 tions are secondary conditions. In the case of one film the water fell 4 

 or 5 inches and thin transparent strands and films of jelly extended from 

 the original mass or disc on the water's surface to branches suspended 

 above the water, thus showing the original attachment of the film. 

 The jelly of this disc could be lifted 4 or 5 inches above the water, and 

 yet keep the connection with the main mass. In another instance a 

 disc was laid, and in one day's time the water rose 8 inches, but the 

 mass retained its attachment to the twigs 8 inches beneath the new 

 water-level, and the former discoidal form changed to the string-like 

 form. 



On June 16, 1913, when we discovered some 7 or 8 egg-complements, 

 considerably more light on the egg-laying was revealed. More than 

 ever are we of the opinion that in the expulsion of the eggs the two 

 forms, green-frog and bullfrog, agree. In several of the complements, 

 the egg-masses were in brush (Plate xx, Fig. 1) near the bank's edge, 

 and all of these were of the film type or originally were. In one case 

 the eggs had the spoiled appearance which green-frog eggs sometimes 

 have when they have been stranded high and dry. The fresh films, 1 

 feet or more in diameter, we could easily detect because of the great 

 amount of air-bubbles in the mass. 



Along the east edge of this particular lake occurs the deepest water 

 and here for many years the tadpoles have often transformed. We 



