. Carnegie Institution of Washington publication. 42 SELECTION IN CLADOCERA ON THE BASIS OF to bear on the general vigor of the stock were tabulated. In con- sidering this point three criteria of the general vigor of the material were used, the age of the mother at the time her first brood was produced, the number of young in her first brood, and the interval between the first and second broods. From a general knowledge of the material and use in other connections of these measures of the vigor of the material, the writer can state that these are satisfactory criteria. Figure IA shows graphica
. Carnegie Institution of Washington publication. 42 SELECTION IN CLADOCERA ON THE BASIS OF to bear on the general vigor of the stock were tabulated. In con- sidering this point three criteria of the general vigor of the material were used, the age of the mother at the time her first brood was produced, the number of young in her first brood, and the interval between the first and second broods. From a general knowledge of the material and use in other connections of these measures of the vigor of the material, the writer can state that these are satisfactory criteria. Figure IA shows graphically the average number of young in the first brood for Line 695 by the two-month periods of the experiment. Figure IB shows the average age of mother for the Bame periods. 1912 1913 1914 1915 1916 4-5 8-9 12-1 4-5 8-9 12-1 4-5 8-9 12-1 4-5 8-9 12-1 4-5 8-9 10 00 t ! -, 4-5 8-9 12-1 4-5 8-9 12-1 4-5 8-9 12-1 4-5 8-9 - 12-1 4-5 8-9. - 00 FIGURE 1.—Line 695. Reproductive vigor. A. Average number in the first brood by two-month periods. The vertical scaling above the base-line indicates the number of young; the horizontal scaling, the two-month periods of the experiment. Solid circles show positions for the plus strain; open circles for the minus strain. B. Average age of mothers at time first brood was produced. Vertical scaling below the base-line indicates the number of days. C. Actual values of reproductive indices (average number of young in first brood divided by average age of mother at time first brood was produced). Vertical scaling indicates the numerical values of the reproductive index. Each numerical value of the reproductive index (in C) is obtained by dividing the corresponding numerical value in A by the corresponding numerical value in 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 work
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