The Journal of experimental zoology . 8 .. 31 .. 32 33 34 35 36 37 38 39 40 Average of j emale flies 17 to 19 hours old 1 ... 3 5 6 10 58 ROBERT STANLEY McEWEN TABLE 1—Continued 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 50,6 41 42 43 44 45 46 47 48 49
The Journal of experimental zoology . 8 .. 31 .. 32 33 34 35 36 37 38 39 40 Average of j emale flies 17 to 19 hours old 1 ... 3 5 6 10 58 ROBERT STANLEY McEWEN TABLE 1—Continued 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 50,6 41 42 43 44 45 46 47 48 49 50 ing all the groups in each series. This was done by averagingthe corresponding tests in each group of the same age and sex(table 1, graph 1). Fatigue curves for flies of different ages Average of seven cards of flies 4-6 days old Average of seven cards of flies 4-6 days old ___^Average of five cards of flies 16-18 hoiue old-•- ? -Average of five cards of flies 16-18 hours old. Graph 1 It appears that the younger flies are rather less phototropic,or at least less active, than those 4 or 5 days old. Also they tiremore easily. Furthermore, although in the younger groups thefemales are consistently above the males, in the older groups themales, after the first few tests are quite the equals of the result is substantially in accord with that obtained in mypreliminairy tests. REACTIONS TO LIGHT AND GRAVITY IN DROSOPHILA 59 As has been noted, the older females gain rather less rela-tively in speed than the older males. This, it appears, mightvery likely be due to the fact that the female is gradually weigheddown by the growth of her eggs. Indeed, it is known that thesedo not reach their full size for 4 or 5 days, the time varying some-what with the abundance of food. This suggested the experi-ment of running some insects of both sexes through a series oftests to be made daily for a period of two weeks, during whicht
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Keywords: ., bookauthorwi, bookcentury1900, bookdecade1910, booksubjectzoology
