Volume 1

Cassell's book of birds / From the text of Dr. Brehm. By Thomas Rymer Jones.

  • Brehm, Alfred Edmund, 1829-1884.
Date:
[1869-1873?]
Catalogue details

Licence: Public Domain Mark

Credit: Cassell's book of birds / From the text of Dr. Brehm. By Thomas Rymer Jones. Source: Wellcome Collection.

    20/351 (page 5)
    it is plain that by some mechanical means or other they catch or clasp among themselves, thereby giving to the web its closeness and compactness of texture. Nor is this all. When two laminae which have been separated by accident or design are brought together again, they immediately reclasp; the connection, whatever it was, is perfectly restored, and the web of the feather becomes as smooth and firm as if nothing had happened to it. Draw your finger down the feather, which is, so to speak, against the grain, and you will probably destroy the junction between some of the contiguous laminae; draw your finger up the feather in the opposite direction, and you restore all to their former state of coherence. This is no common contrivance. Let us now inquire concerning the mechanism whereby it is effected. The laminae above mentioned, examined indi- vidually, are found to be provided with vast numbers of long fibres, or teeth, which project from their edges in such a manner that, when placed in contact, those of contiguous laminae hook and grapple together. The fibres are extremely minute; indeed, fifty of them have been counted by means of the microscope in the space of the g^th of an inch. Every fibre is crooked, but bent after a definite manner ; those that proceed from one edge of a lamina are long, flexible, and bent downwards, whereas those that proceed from the oppo- site edge are shorter, firmer, and turned upwards. The manner in which they are united is, therefore, as follows : When two contiguous laminae are pressed together, so that the long fibres are forced far enough over the short ones, their crooked parts fall into the angles formed by the crooked parts of the others, just as the latch of a door falls into the cavity of the catch fixed to the door-post, and there hooking itself, fastens the door. This admirable structure, which may be readily seen with a very ordinary microscope, ensures not only the union of the laminae, but renders it possible that when any two of them have been separated by violence they will become re-connected with facility and expedition*. In the ostrich, this apparatus of crotchets and fibres, of hooks and eyes, is wanting; the filamentary laminae hang loose and separate, forming a kind of down; but such a plan of con- struction, however it may fit the plumes for the flowing honours of a lady’s head-dress, must be considered as detrimental to the bird, inasmuch as wings composed of such feathers, although they may assist in running, will not serve for flight. The power of inflating their whole body with air, and the possession of feathers, are therefore the most distinctive endowments of a bird, inasmuch as these attributes are quite peculiar to the class. To creatures thus gifted with strength and activity so extraordinary, it is manifest that percep- tions of great acuteness are requisite, corresponding with the rapidity of their movements and the Fig. 3.—NASCENT FEATHER OF A CHICKEN. c, the External Horny Sheath, slit open; d, d, Web of the Feather produced in successive layers from the central stem, e.