Page:The Zoologist, 4th series, vol 2 (1898).djvu/500

468 reasons for thinking that symmetrical colour and marking is kept up in nature for facility of recognition, a factor essential to preservation and to the formation of new species." Mr. Bateson combats the view that variability of domestic animals is markedly in excess of that seen in wild forms. He adduces the great variability of the teeth of the large Anthropoids compared with the rarity of variations in the teeth of other Old World Monkeys, and the comparative rarity of great variations even in man:—"If the Seals or Anthropoids had been domesticated animals, it is possible that some persons would have seen in their variability a consequence of domestication." As regards colour, the same author is more emphatic. To use his own example:—"I go into the fields of the north of Kent in early August, and sweep the Ladybirds off the thistles and nettles of waste places. Hundreds, sometimes thousands, may be taken in a few hours. They are mostly of two species, the small Coccinella decempunctata or variabilis and the larger C. septempunctata. Both are exceedingly common, feeding on Aphides on the same plants in the same places at the same time. The former—C. decempunctata—shows an excessive variation both in colours and in pattern of colours, red-brown, yellow-brown, orange, red, yellowish white, and black in countless shades, mottled or dotted upon each other in various ways. The colours of Pigeons or of cattle are scarcely more variable. Yet the colour of the larger C. septempunctata is almost absolutely constant, having the same black spots on the same red ground. The slightest difference in the size of the black spots is all the variation to be seen. (It has not even that dark form in which the black spreads over the elytra until only two red spots remain, which is to be seen in C. bipunctata.) To be asked to believe that the colour of C. septempunctata is constant because it matters to the species, and that the colour of C. decempunctata is variable because it does not matter, is to be asked to abrogate reason."

If we consult Mr. Gladstone's 'Impregnable Rock of Holy Scripture,' we shall be induced to believe that such markings may have arisen by a partial or further process of assimilative