Page:Popular Science Monthly Volume 81.djvu/374

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368
THE POPULAR SCIENCE MONTHLY

usually these statements are to the effect that the bird's ovary contains "several hundred" ova.

Table I

Showing the Number of Visible Oocytes in the Ovary of Certain Fowls

Case No. Bird No. Breed Winter Pro-
duction
Total Visible
Oocytes
1 8,021 Barred Plymouth Rock 3 1,228
2 8,017 Barred Plymouth Rock 0 1,666
3 8,030 Barred Plymouth Rock 0 914
4 8,005 Barred Plymouth Rock 5 1,174
5 1,376 Barred Plymouth Rock 3 2,306
6 8,018 Barred Plymouth Rock 0 1,194
7 8,009 Barred Plymouth Rock 0 2,101
8 8,010 Barred Plymouth Rock 5 1,576
9 425 Barred Plymouth Rock 0 1,521
10 3,546 White Leghorn 54 2,452
11 2,067 White Leghorn 32 3,605
12 3,453 White Leghorn 0 1,701
13 3,833 White Leghorn 0 2,145
14 52 Cornish Indian Game 13 1,550
15 71 F1 Cross 106 2,000
 

Not only is the absolute number of oocytes large, but it is also very much larger than the number of eggs which any hen ever lays. A record of 200 eggs in the year is a high record of fecundity for the domestic fowl, though in exceptional cases it may go even a hundred eggs higher than this. But even a 200-egg record is only a little more than a tenth of the average total number of visible oocytes in a bird's ovary, to say nothing of the probably much larger number of oocytes invisible to the unaided eye, but capable of growth and development. In other words, it is quite evident from these figures that the potential "anatomical" fecundity is very much higher than the actually realized fecundity. This is true even if we suppose the bird to be allowed to live until it dies a natural death.

An examination of the table in detail indicates that there is no very close or definite relationship between the number of visible oocytes on the ovary and the winter production of a bird. Thus No. 1,367 and No. 3,546 each have about the same number of visible oocytes, yet one has a winter production record 18 times as great as the other. Again No. 71 with the extraordinarily high winter record of 106 eggs has only a little more than one half as many visible oocytes as hen No. 2,067, whose winter production record is only 32 eggs. Again, No. 71 with its 106 record has very nearly the same oocyte count as No. 8,010 with a winter record of zero. In general it may be said that the present figures give no indication that there is any correlation between fecundity as measured by winter production, and the number of oocytes in the ovary. Of course, the present statistics are meager. More ample figures are needed (and are being collected) from which to measure the correlation between actual and "anatomical" fecundity.