. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. RECRUDESCENCE OF BOBOLINK TESTES 259 250 100 50 25 10 5 en Ld t- CO UJ. c/> a °m ' o 18 hr p • l7 " 2 5h — ~^/ • Q 16 A A | ni t ia I 0 10 20 30 40 50 60 1 _ i I i i i i i _ | _ i i _ i i DAYS OF LONG PHOTOPERIOD (p) NOV. i DEC. i JAN FIGURE 2. Recrudescence of bobolink testes, as indicated by weight, when exposed in early November to photoperiods of 15, 16, 17 and 18 hours. Lines indicate k values of , and (see text). already developed the black beak pigmentation indicative of the production of mal
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. RECRUDESCENCE OF BOBOLINK TESTES 259 250 100 50 25 10 5 en Ld t- CO UJ. c/> a °m ' o 18 hr p • l7 " 2 5h — ~^/ • Q 16 A A | ni t ia I 0 10 20 30 40 50 60 1 _ i I i i i i i _ | _ i i _ i i DAYS OF LONG PHOTOPERIOD (p) NOV. i DEC. i JAN FIGURE 2. Recrudescence of bobolink testes, as indicated by weight, when exposed in early November to photoperiods of 15, 16, 17 and 18 hours. Lines indicate k values of , and (see text). already developed the black beak pigmentation indicative of the production of male sex hormone, and testicular weights ranged from about 20 mg to more than 100 mg. Four birds of similar history, which were killed at the same time after 16 days on 14-hour photoperiods, each had testes weighing less than mg (average mg, Figure 1). 3. 17-lwnr, 16-hour and 15-hour photoperiods (Figure 2) Although the "17-hour" birds lagged a little behind the "18-hour" birds with respect to average time of development of beak pigmentation, the samples do not show any marked difference in the rate of recrudescence. On the 16th day, weights of testes of six birds in the "17-hour" group ranged from about 30 mg to just over 100 mg (compared with 20 mg to 115 mg in the "18-hour" group). At this time there still were six birds in the "17-hour" group that did not show beak pigmentation; by the 22nd day their testicular weights considerably exceeded in value those of the first sample, ranging from 60 mg to 164 mg, with an increase in the mean from 56 mg to 104 mg. The rate of recrudescence in the "16-hour" group was definitely lower than in the previous two groups, weights of six pairs of testes on the 16th day ranging from 6 mg to 60 mg. By the 22nd day some were still quite small ( mg and 10 mg in two birds) but a number were of the same size as in "17-hour" birds at this time (17-hour: 60 mg to
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
