. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. 2^6 DISCOVERY REPORTS oestrus, therefore, the majority (12 out of 17 = 70 per cent) of these Sei whales became pregnant at the first ovulation, but thereafter Fig. 81 suggests that there is an average of three dioestrous cycles at each oestrus. The breeding season appears to be determined by the physiological condition of the females only because, as has been shown above, no marked seasonal activity of the male structures has been found. It is probable that oestrus lasts for some time and is mad
. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. 2^6 DISCOVERY REPORTS oestrus, therefore, the majority (12 out of 17 = 70 per cent) of these Sei whales became pregnant at the first ovulation, but thereafter Fig. 81 suggests that there is an average of three dioestrous cycles at each oestrus. The breeding season appears to be determined by the physiological condition of the females only because, as has been shown above, no marked seasonal activity of the male structures has been found. It is probable that oestrus lasts for some time and is made up of any number up to 4 di- oestrous cycles, until fertilization takes place. The unfruitful cycles are presumably due to absence of males from the neighbourhood of the female at the time of oestrus, though they may no doubt be due to unsuccessful matings, or other un- known factors. The sexual cycle of the female Sei whale may therefore be summarized diagrammatically as in Fig. 82 which represents two years of the whale's Number of Corpora Lutea Fig. 81. Sei whale. Females. Frequency of corpus luteum 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 Institute of Oceanographic Sciences (Great Britain); National Institute of Oceanography of Great Britain; Great Britain. Colonial Office. Discovery Committee. London ; New York : Cambridge University Press
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Keywords: ., bookcentury1900, booksubjectocean, booksubjectscientificexpediti
