. The anatomical record. Anatomy; Anatomy. RELATION OF ACiE TO FERTILITY IN RAT 275 ords of ii luiinber of females but from u random collection of litters cast by females of unknown a^(\ Litter size in various strains of rats cannot be pi-operly comparetl until litter records for the several strains have been collected in a similar manner. The relation between the age of the mother and litter size is shown by the graph in figure 2. The data used in construct- ing this graph are given in table 2. The graph reaches its maximum when the females are prac- tically at the beginning of their reproduc
. The anatomical record. Anatomy; Anatomy. RELATION OF ACiE TO FERTILITY IN RAT 275 ords of ii luiinber of females but from u random collection of litters cast by females of unknown a^(\ Litter size in various strains of rats cannot be pi-operly comparetl until litter records for the several strains have been collected in a similar manner. The relation between the age of the mother and litter size is shown by the graph in figure 2. The data used in construct- ing this graph are given in table 2. The graph reaches its maximum when the females are prac- tically at the beginning of their reproductive activity (, at. Z40 270 300 33D 3S0 330 430 450 460 Fig. 2 Graph showing, for the entire series, the relation of the age of the mother to the average size of the litter (data in table 2). 120 days of age), and then declines very gradually approximat- ing zero when the females are eighteen months old. Fertility in the rat, measured by the size of the litters cast, is thus found to be correlated with the age of the mother at the time that parturition occurs. There is a possibihty that the number of the pregnancy is a factor that influences the size of the litters cast. In order to analyze the data on this basis the records have been arranged according to the position of each litter in a Utter series and are given in table 3. When the data are arranged as in table 3 it is found that the second litter is the largest of the series. This result is in accord with the observations of Crampe ('84) and of King and Stotsen-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Bardeen, Charles Russell, 1871-1935, ed; Boyden, Edward A. (Edward Allen), 1886-1976; Bremer, John Lewis, 1874- ed; Hardesty, Irving, b. 1866, ed; American Association of Anatomists; American Society of Zoologists; Wistar Institute of Anatomy
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectanatomy, bookyear1906
