J
Possible Date of Pairing.
Age of Fortus.
Equals Days Plus 61 Days of Subsequent Preliminary
Growth, Development.
APPENDICES,
123
195, 207, and 287, as to evidence of recent impregnation or copulation (see above at pp. 110-114) we have evidence of pairing in December and January as well. In the following table the distribution of the pairings in the corresponding months of the northern and southern hemispheres is shown :-
"ו
September 3 (1913)
Month. October
November December
(4) January (5) February
March
(7) April (8) May (9) June
(10) July
(11) August
(12) September.
mm.
mm.
1913, December 19
1,700
1,400
66
127
August 14 (1913)
20
1,725
19
1,425
67
128
14
**
18
1,650
»
1,350
64
125
15 12
19
"
11
1,600
1,300
61
122
19
"
"
1914, January 15...
2,130
1,830
86
147
21
""
บ
1913, December 18
1,400
1,100
52
113
22
11
18
1,400
1,100
52
113
22
1914, January 9
1,980
1,680
79
140
2241
"
15
"
12...
1,980
1,680
79
140
25
11
1918, December 20
1,425
1,125
53
114
28
11
"
1914, January 9
1,725
1,425
67
128
1918, December 22
1,120
820
39
100
18
1914, January 14...
1,600
1,300
61
122
14
>>
**
1918, December 13
585
285
13
74
30
19
19
635
335
16
77
October
8
1914, January 15...
509
209
10
71
November 5 "J
SOUTH GEORGIA
(from Whalers' reports to
the British Museum)—
1913, December 17
2,590
2,290
108
169
Joly 1
13
"
2,440
2,140
101
162
4
11
1914, January 13...
3,050
2,750
129
190
}
7 (1918)
March 19
4,270
3,970
187
248
14
"
13
April 2
4,575
4,275
201
262
14
"}
15
1913, December 13
2,135
1,835
86
147
19
"
11
1)
"
1,830
1,530
72
133
91
17
22
1,830
1,530
72
133
1914, January 5
2,135
1,835
86
147
1918, December 9
1,525
1,225
58
119
12
"
1914, March 20
3,660
3,360
158
219
"
1913, December 13
13 (1913)
1,525
1,225
18
1,525
1,225
1914, January 10...
2,135
1,835
1913, December 6
1,370
1,070
1914, January 12...
2,135
1,835
1918, December 30
1,830
1,530
18
#
15
1,525
1,225
20
1,525
1,225
1914, January 5
1,830
1,530
April 2
3,660
3,360
158
1913, December 31
1,525
1,225
January 7
1,220
920
************
1-19
16
13
119
16
"
147
11
111
17
86
147
133
119
18 (1913)
19
21
119
28
"
133
25 (1913)
219
13
26 (1913)
119 104
September 3
25 (1913)
Month.
NORTH ATLANTIC.
Number of pairings.
2
2
4
17
38
22
11
5
2
?
1
SOUTH ATLANTIC.
104
Number of pairings.
(1) April.
Major Barrett-Hamilton's From
observations. Companies' records. Total.
August 11
11 (1913)
16 (1913)
May.
June.
July
(5) August
(6) September
October
November
4
14
4
1
1
(9) December (some evidence).
(10) January (some evidence).
(11) February.
(12) March.
24
742
23
=8811
28
6
47
PUBLIC RECORD OFFICE
བ།
Reference :-
mmimmimi.C.O. 885
23 PUBLIC RECORD OFFICE, LONDON
ALLY WITHOUT PERMISSION OF THE BE REPRODUCED PHOTOGRAPHIC- COPYRIGHT PHOTOGRAPH-NOT TO
In the above table all the foetuses enumerated in the lists at pp. 115-118 above are arranged in the order of their "pairing dates." Further research is greatly to be desired, and it may show that the preliminary development of the foetus takes more than 61 days; that its subsequent growth occupies more or less than 273 days; and that the length of the finner at birth is more or less than 6,100 mm. In these circumstances it will be understood that the pairing dates qua dates may
have little or no value, and that at best they can only be regarded as purely tentative estimates; nevertheless, these dates are all subject to the same errors and so are fairly comparable; therefore they may, and in fact appear to, afford valuable infor- mation regarding the nature and length of the breeding season of the finners.
With regard to the simple pregnancies the table deals with 104 cases from the North Atlantic, 24 cases noted by Major Barrett-Hamilton at South Georgia, and 23 cases recorded by four of the companies working in the Dependency in their reports to the British Museum. It would appear that in the North Atlantic pair- ing may happen in any month of the year, with the apparent exception of September and possibly of July, the available observations from the South Atlantic show pair- ings throughout the period between July and November, and if we take into account the notes made by Major Barrett-Hamilton upon the females Nos. 37. 38, 65, 79.
From this summary it seems to be clear that both in the North and in the South Atlantic the great majority of the finners pair during a definite season. If the factors and method used in computing the "pairing dates" be sound this definite season must fall in the spring, the rut apparently culminating in February in the northern, and in the corresponding month of August in the southern hemisphere.
At South Georgia the number of corpora lutea, when any were found, in con- nexion with the ovaries of the finners, varied between one and seven; in pregnant females one corpus luteum was enlarged and was thus apparently connected with the shedding of that ovum which was subsequently impregnated. The large number of corpora lutea sometimes present points to the fact that, in those cases in which the earlier cestra are unsatisfied by effective pairing, the sexual season of the finners may be of a long and polycestrous character.
In his note on the female No. 50 (see above at p. 111) Major Barrett-Hamilton suggested that the interval between each estrus may be one of three or four weeks. Professor Collett says that, among Norwegian finners, twins are found in no fewer than one in every 20 pregnancies examined, and, further, that in those cases in which the sex of the foetuses has been determined the twins have, as a rule, been found to be a male and a female. Certain of these cases of twins are of great interest and they appear to me to give evidence as to the length of the interval between the successive mestra. Six instances are dealt with in the table at p. 121. In the first three cases (4th September, 1903. August, 1882, and 1st August, 1884) the twins were
No comments yet.
Private notes are available after approval.