THE AMPHIBIA OF OKLAHOMA 



to total volume, and while the ovarian volumetric percentage does not always 

 seem to indicate the stage of development of the oocytes, the trend of changes 

 is very clear. 



Summary 



One hundred and seventy-nine females of Acris crepitans were studied 

 both macroscopically and microscopically with regard to changes occurring 

 in their ovaries during the course of a year. An annual cycle in the develop- 

 ment of the ovaries, beginning in late September and terminating in late 

 August or early September, is indicated by the curve of average monthly 

 percentages of ovarian volume, the relative sizes of the oocytes during each 

 month, the time and manner of yolk formation, the movement of the nucleoli 

 from the periphery of the nucleus in September to a position of close prox- 

 imity to the chromosomes in the center of the nucleus in the breeding months, 

 and, in order to make room for the new generation of oocytes beginning de- 

 velopment, the degeneration and resorption during the breeding season of 

 all well-developed oocytes which do not escape from the ovary. The breeding 

 season, as determined from this study, extends during the years of these ob- 

 servations from the latter part of July to the early part of September. 



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140 



