THE AMPHIBIA OF OKLAHOMA 



development of the ovary. Likewise, frogs collected during August, 1936, had 

 lower percentages than did those collected during August of other years. 

 The general average for August is slightly lower than that of July, with a 

 rather wide range among individuals. Thus the average ratios of ovarian 

 volume to that of the body of frogs collected during the months of October 

 through March represent the lowest of the year, while the peak is reached 

 in May. 



External Changes in the Character of the Ovaries 



The female genital system of specimens of Acris crepitans is similar in 

 all essentials to that of the typical frog. A detailed description of the same 

 will not be included in this report, the interest of the observations made lying 

 solely in the changes of the ovaries during the year. 



Ovaries of frogs collected in September and October are shrunken, un- 

 pigmented, and contain few well-developed oocytes. As will be noted later, 

 a significant difference is found in the appearance of these ovaries and those 

 of frogs in the August collections, a difference which marks the end of the 

 breeding season and the beginning of the new generation of oocytes. The 

 small oocytes, entirely lacking in pigmentation, which are found in ovaries 

 of specimens collected and fixed during September and October are almost 

 translucent, although the nuclei are distinctly visible. Ovaries of frogs taken 

 during November and December are quite similar externally to those of 

 October. Although the oocytes vary slightly in size, no advanced stages are 

 seen in the average specimen. 



Ovaries of frogs collected during January were not available for gross 

 study. The ovaries of those specimens fixed in February are entirely lacking 

 in pigmentation, and when seen under a dissecting microscope show no well- 

 developed oocytes. Their shape and general appearance is much like that of 

 a mulberry, small oocytes causing slight protrusions over the entire surface 

 of the ovary. 



The ovaries of frogs in collections of March are quite similar in appear- 

 ance to those which are typical of February, development externally showing 

 little progress. Pigmentation is lacking and the increase in size of the oocytes 

 is almost negligible. Ovaries of specimens taken during April are slightly 

 advanced in development over those of March. Although of varying sizes, 

 none of the oocytes show marked development. Changes in both pigmenta- 

 tion and size occur at the end of April, and many well-developed, deeply 

 pigmented oocytes are found in ovaries of animals collected in May. The 

 range of size is great, indicating the presence ol \arious stages of develop- 

 ment within a single ovary. 



Frogs collected during June have ovaries so greatly increased in xolume 

 by the rapidly developing oocytes as to fill the entire body cavity, although 

 of the 179 frogs examined there was none in which eggs were found free in 

 the cavity either during this month or other months, as had been reported 

 for Hufo by King ( 1905) in numerous cases, anti tor Oyptobranchus by 

 Smith (1912) in very few. 



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