. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. NEWLY MATURE FEMALES 41S The mean growth curve has been continued as a broken line, increasing very slightly from June to December and then increasing again during the second feeding season after puberty. At 2 years after puberty the mean length is shown as 69-6 ft. If the average rate of ovulation is 1-4 per year (below p. 465) then 2 years after puberty there are expected to be on average 2-8 corpora and from Text- fig. 25 the mean length at 2-8 corpora is 69-6 ft. The growth previous to puber
. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. NEWLY MATURE FEMALES 41S The mean growth curve has been continued as a broken line, increasing very slightly from June to December and then increasing again during the second feeding season after puberty. At 2 years after puberty the mean length is shown as 69-6 ft. If the average rate of ovulation is 1-4 per year (below p. 465) then 2 years after puberty there are expected to be on average 2-8 corpora and from Text- fig. 25 the mean length at 2-8 corpora is 69-6 ft. The growth previous to puberty is also suggested as a broken line, to indicate that in the feeding season before puberty growth is more rapid, as is probable in the primiparous feeding females. If this line of argument is correct, then puberty usually succeeds both a period of rapid growth, and a northward migration when day length is increasing (see below, p. 421). 72 -1 A - - BC - —DF-. 'jvTa mJJaSONDJFMAMJJASONDJFMAMJ MONTHS FEEDING PAIRING FEEDING PARTURITION FEEDING -| Text-fig. 39. Growth of newly mature females indicated by mean length ± a, ±2 A, at puberty; B, first pregnancy, o corpus albicans;C, one nulliparous ovulation; D, first lactation or resting period; F, second pregnancy, 1 corpus albicans. See text for explanation. The position of the remaining group, of females in their second pregnancy with one corpus albicans and resting mammary glands (F), must now be discussed. These are females which have become pregnant again at the first ovulation after the termination of the first pregnancy. It seems most probable that the origin of this second pregnancy is either a post-partum ovulation (shown below, p. 429, to be a normal feature of the reproductive cycle in female fin whales and some other species) and or an ovulation following the termination of lactation upon loss of the calf. It is, however, certain that some, possibly all, of these first-lactation females do not experience a pos
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