| OCR Text |
Show 112 INCREASED FERTILITY CHAP. XVI. down to lowland pastures frequently bear twins. This difference apparently is not due to the cold of. the higher land, for sheep and other domestic animals are sa1d to be extr~mely prolific in Lapland. Bard living, also, retards. the penod at which animals conceive; for it has Leen found ch. advantageous in the northern islands of Scotland to allow cows to bear calves before they are four years old.30 Birds offer still better evidence of increased fertility from domestieation: ~· the hen of the wild Gallus banlciva lays from six to ten eggs, a number which would be thought nothing of with the domestic ben. The wild duck lays from five to ten eggs; the tame ohe in the com. e of the year from eighty to one hundred. The wild grey-lag goose lays from five to eiaht eggs; the tame from thirteen to eighteen, and she lays a second ti~e; as 1\Ir. Dixon has remarked, "high-feeding, care, and moderate warmth induce a habit of prolificacy which becomes in some measure hereditary." Whether the semi-domestica.tod dovecot pigeon is more fertile than tho wild rock-pigeon, C'. livia, I know not; but the more thoroughly domesticated breeds are nearly twice as fertile as dovecots: the latter, however, when caged and highly fed, become equally fertile with house pigeons. The peahen alone of domesticated birds is rather more fertile, according to some accounts, when wild in its native Indian home, than when domesticated in Europe and exposed to our much colder climate. 51 vVith respect to plants, no one would expect wheat to tiller more, and each ear to produce more grain, in poor than in rich soil; or to get in poor soil a heavy crop of peas or beans. Seeds vary so much in nnmber so For cats and dogs, &c., see Bellingeri, in 'Annal. des Sc. Nat.,' 2nd seriPs, Zoolog., tom. xii. p. 155. For ferrets, Becl1stein, 'Naturgeschichte Deutschland.o,' Bam1 i., 1801, s. 786, 795. For rabbits, ditt.o, s. 1123, 1131 ; and Bronn's 'Geschichte der Natur," B. ii. s. 99. For mountain sheep, ditto, s. 102. For the fertility of the wild sow, see Bechstein's 'Natmgesch . Deutsch lands,' B. i., 1801, s. 534; for the domestic pig, Sidney's edit. of Youatt on the Pig, 1860, p. G2. With respect to Lapland, see Acerbi's 'Travels to the North Cape,' Eng. translat., vol. ii. p. 222. A bout the Highland cows, see Hogg on Sheep, p. 263. 3l For the eggs of Gallus bankiva, see Blyth, in 'Annals aud Mag. of Nat. Hist.,' 2nd series, vol. i ., 1848, p. 456. For wild and tame ducks, Macgillivray, 'Briti sh Birds,' vol. v. p. 37; :-llld 'Die Enten,' s. 87. For wild geese, L. Lloyd, 'Scandinavian Adventures,' vol. ii. 1854, p. 413; and for tame geese, ' Ornamental Poultry, ' by Rev. E. S. Dixon, p. 139. On the breeding of pigeons, Pistor, 'Das Ganze der Taubenzucht,' 1831, s. 46; and Boit::ml and Corbie, 'Les Pigeons,' p. 158. With respect to peacocks, according to Temminck (' Hist. Nat. Gen. des Pigeons,' &c., 1813, tom. ii. p. 41), tbe ben Jays in India even ar; many as twenty eggs; but according to Jerdon aud another writer (quoted in Tegetmeier's 'Poultry Book;' 1866, pp. 280, 282), she there lays only from four to nine or ten eggs: in England she is ~aid, in the 'Poultry Book,· to lay five or six, but another writer says from eight to twelve eggs. CIIH. XVI. FROl\1 DOMESTICATION. 113 that it is difficult to estimate them; but on comparing beds of carrots saved for seed in a nursery garden with wild plants, the former seemed to produce about twice as much seed. Cultivated cabbages yielded thrice as many pods by measure as wild cabbages from the rocks of South Wales. The excess of benies produced by the cultivated Asparagus in comparison with the wild plant is enormous. No doubt many highly cultivated plants, such as pears, pineapples, bananas, sugar-cane, &c., are nearly or quite sterile; and I am inclined to attribute this sterility to excess of food and to other unnatural conditions; but to this subject I shall presently recur. ln some cases, as with the pig, rabbit, &c., and with those plants which are valued for their seed, the direct selection of the more fertile individuals has probably much increased their ferti lity; and in all case~ this may have occurred indirectly, from the better chance of the more numerous offspring produced by the more fertile individuals having survived. But with cats, ferrets, and dogs, and with plants like carrots, cabbages, and asparagus, which are not valued for their prolificacy, selection can h~ve played only a subordinate part; and their increased fertility must be attributed to the more favourable conditions of life under which they have long existed. VOL. II. I |
