Volume 1

The variation of animals and plants under domestication / by Charles Darwin.

  • Darwin, Charles, 1809-1882.
Date:
1888
Catalogue details

Licence: Public Domain Mark

Credit: The variation of animals and plants under domestication / by Charles Darwin. Source: Wellcome Collection.

    198/498 (page 178)
    beak longer by *23 of an inch, whilst its tongue was shorter *by 14 than in the other. With the ijicreased or diminished length of the beak the length of the slit forming the external orifice of the nostrils varies, but not in due proportion, for, taking the rock-pigeon as the standard, the orifice in a Short-faced Tumbler was not shortened in due proportion with its very short beak. On the other hand (and this could not have been anticipated), the orifice in three English Carriers, in the Bagadotten Carrier, and in a Bunt {pigeon cygne), was longer by above the tenth of an inch than would follow from the length of the beak proportionally with that of the rock-pigeon. In one Carrier the orifice of the nostrils was thrice as long as in the rock-pigeon, though in body and length of beak this bird was not nearly double the size of the rock-pigeon. This greatly increased length of the orifice of the nostrils seems to stand partly in correlation with the enlargement of the wattled skin on the upper mandible and over the nostrils; and this is a character which is selected by fancieis. So again, the broad, naked, and wattled skin round the eyes of Carriers and Barbs is a selected character; and in ol )\ ious correlation with this, the eyelids, measured longitudinally, are proportionally more than double the length of those of the rock-pigeon. The great difference (see woodcut No. 27) in the curvatuie of the lower jaw in the rock-pigeon, the Tumbler, and Baga- dotten Carrier, stands in obvious relation to the curvature of the upper jaw, and more especially to the angle formed by the maxillo-jugal arch with the premaxillary bones. But in Carriers, Bunts, and Barbs the singular reflexion of the upper margin of the middle part of the lower jaw (see woodcut No. 25) is not strictly correlated with the width or divergence (as may be clearly seen in woodcut No. 26) ot the premaxillary bones, but with the breadth of the horny and soft parts of the upper mandible, which are always overlapped by the edges of the lower mandible. In Pouters, the elongation of the body is a selected cha- racter, and the ribs, as we have seen, have generally become very broad, with the seventh pair furnished with processes; the