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Show 100 MEANS OF EXPRESSION CHAP. IY. finch of a most irascible disposition, which when approached too closely by a servant, instantly assumes the appearance of a ball of ruffled feathers. He believes that birds when frightened, as a general rule, closely ad press all their feathers, and their consequently diminished size is often astonishing. As soon as they recover from their fear or surprise, the first thing which they do is to shake out their feathers. Tho best instances of this adpression of the feathers and apparent shrinking of the body from fea~·, which Mr. Weir has noticed has been in the quail and grassparrakeet. 15 Th: habit is intelligibl.e in these ?irds from their beino- accustomed, when 1n danger, e1ther to squat on the ~round or to sit motion~ess o~ a branch, so as to escape detection. Though, with buds, an~er may be the chief and commonest cause of the erection of the feathers, it is probable that young c~ckoos when looked at in the nest, and a hen with her chickens when approached by a dog, feel at le~st some terror. Mr. Teo-etmeier informs me that with game·cocks, tho ere~tion of the feathers on the head has long been recoo-nized in the cock-pit as a sign of cowardice. - The males of some lizards, when fighting together during their courtship, expand their throat pouc~es or frills and erect their dorsal crests. 16 But Dr. Gunther does' not believe that they can erect their separate spines or scales. We thus see how generally throughout the two hio·her vertebrate classes, and with some reptiles, the de~·1nal appendages are erected under the influen('o of anger and fear. The movement is effected, as "·c-· u Melopsittacus undulatus. See an account of its habits by Gou1<1, ' Handbook of Birds of Australia,' 1865, vol. ii. p. 82. 16 See, for instance, the account which I have given ('Descent of 1\fn.n,' vo1. jj, p. 32) of an Anolis and Dnll'o. CHAP. IV. IN ANIMALS. 1 1 know from Kollikcr's interestinO' discovery 1.y th t . . b ' u c n-raction of minute, unstriped, involuntary mu ·clc::; 11 often called arrectores pili, which are attach d to tile caps~les of the separate hairs, feathers, &c. By the contraction of these 1nuscles the hairs can be instantly ere.cted, as we see in a dog, being at the same time drawu a httle out of their sockets; they are afterwards quicld y depressed. The vast number of these minute muscle::; ~ver t~e ":hole body of. a .hairy quadruped is astonishing. The .e1 echon of the hair Is, however, aided in some cas s, as With that on the head of a 1nan, by the striped an<l voluntary ~1uscles of the nnderlying panniculus carnosu, s. It Is by the action of these latter muscles, that the hedgehog erects its spines. It appears, also, fron1 the researches of Leydig 18 and others, that striped fib:·:s extend from ~h~ panniculus to some of the larg r hans, such as the Yibrissre of certain quadrupeds. The a.rrectores pili contract not only under the above emotions, but fi,om the application of cold to the surface. I remember that my mules and dogs, brought from a lower and ~armer country, after spending a night on the bleak Cord1llera, had the hair all over their bodies as erect as under tl1e greatest terror. Wo see the samo action in our own goose-slcin during the chill befor a feve~-fit. ~r. Lister has also found, 19 that tickling a nmghbour1ng part of the skin causes the erection and protrusion of the l1airs. From these facts it is manifest that the erection of the dermal appendages is a reflex action, independent 17 Th~se muscles are described in his well-known works. I alll ?rcatly m~ebted t~ this distinguished observer for having given me m a letter mformatwn on this same subject. 18 ' Lchrbuch dcr Histologic des Menschen,' 1857, 8. 82. I owe tu Prof. W. Turner's kindness an extract from this wori~ 19 'Q ~. uarterly Journal of Microscopical Science,' 1853, vol. i. p. 262. |