Theories and facts as to palaeogenesis in its probable influence on the coloration of animals / by Jonathan Hutchinson.

  • Hutchinson, Jonathan, Sir, 1828-1913.
Date:
1912
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Licence: In copyright

Credit: Theories and facts as to palaeogenesis in its probable influence on the coloration of animals / by Jonathan Hutchinson. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    is a ring of lighter grey tint tending to yellowish, whilst in one this circle around the eye has an ascending branch from the inner canthus which runs upwards to the forehead—the xanthelasma patch. This upward streak occurs in only one of the animals, and is very definite. Piebald. It is more difficult to give a technical definition of piebald than some may imagine. We must not here use it with the vagueness which would imply only that the animal is parti- coloured. Under the term of piebald with reference to horses, dogs, cattle, &c., it must he allowed to mean that there are abrupt, map-like patches of different colour, and usually of black or red upon a ground of white. Seldom are there three colours, but they are common in the instance of cats and cattle. In piebald animals the patches of different colour are placed for the most part without order, and no pattern whatever can be traced. Often, however, perhaps even usually, some approach to bilateral symmetry may be made out, and such symmetry is often quite definite in one part of the body while it is quite lost in another. It may be sometimes shown by patches on the two sides, which correspond as to location but look very different owing to their conspicuous deviations as to size. I do not know of any examples of wholly one-sided coloration in wild animals, whilst there are many which show equatorial limitation (as if by a girdle) with tolerable abruptness. Some- times it is the upper half and sometimes the lower which shows conspicuous markings, and almost always the limitation, if it is abrupt, concerns streaks only. In disease equatorial limitation is common enough in connec- tion with injuries, or some disease of the nervous system. So, of course, is the unilateral or hemiplegic type. To the equa- torial the term “ para ” may perhaps be applied. The Bangalore Cat. The Bangalore Cat, from an engraving which I possess, shows well-marked rings on its thighs and lower part of tail, none on the trunk, nor any on the legs. The streaks in the middle of its forehead are a little indefinite, and there are none whatever on the body of the animal. The tip of the tail is black, and five very definite rings are present above the black tip. The rest of the tail has no rings. The level of the rings is on the lower part of the tail and on the upper extremities about the same (horizontal limitation). The Porcupines. The quills of the common Porcupine are grown almost solely on the hinder half of its back. On the front of its hack, neck, and top of head there is a mane of long hairs, but they do not develop