A C U L E U S. 



a single muscJc of the feet. When reposing, the head 

 is either turned under the wing, or it is bent back, by 

 contrary flexures of the neck, till it rests on or near the 

 shoulders. The whole body is, in fact, concentrated 

 upon that part of the spine which has little or no 

 motion by joints. 



The repose of all vertebrated animals is concentrated 

 in the spinal column, which alone is very strong pre- 

 sumptive evidence that the brain and its spinal con- 

 tinuations are the centres or sources of all animal 

 action ; but the position of repose in that column 

 varies with the structure and habits. When the spine 

 is flexible, the position of repose is nearly half way 

 between the extremes of the range of motion, or rather 

 that range is divided in the exact ratio of the powers 

 of the flexor and extensor muscles ; and the articu- 

 lation feels loose, so that the part may be moved to 

 some distance either way, with little effort, and no 

 pain or even disturbance. In the bird, however, which 

 holds its perch by tendinous elasticity, the flexure of 

 the neck is beyond that position which would be repose 

 in a quadruped, so that the tendons of the extensors 

 are tightened ; and any cause, which agitates the 

 perching feet, at the same instant brings the neck 

 into action, and extends, elevates, or depresses the 

 head, to the exact extent which the balance requires. 

 Thus, there is in the very structure of the bird a means 

 of resisting any casualty that might drive it from its 

 perch, and that without any more of what we call will 

 or even instinct in the creature itself, than there is will 

 or instinct in the breathing or the circulating of the 

 blood in man while he is asleep. The sleep, even 

 when most profound and unbroken, is thus not a sleep 

 of the whole animal, for the functions of certain parts 

 of it are going on, and others are ready to obey, not 

 the will of the animal, but external circumstances, as 

 for instance the freshening or abating of the wind. 

 The bird is thus never altogether asleep, neither can 

 it be considered as wholly awake, until all parts of the 

 system are in the full bent of their action. 



The nicety with which branch birds bend the posi- 

 tions of their bodies to the fitful wind, or rather the way 

 in which, without contrivance or purpose in either, the 

 bird and the wind act in concert, are well worth 

 noticing. The perch moves in obedience to the wind, 

 or other cause by which it is agitated, and the bird 

 moves along witn it ; but the bird has also a compen- 

 sating motion in itself, wholly without design, by means 

 of which, up to a certain degree of agitation in the 

 perch, it maintains its balance with closed wings. 

 When the agitation becomes too great for that, the 

 wings are put out, just as a rope-walker uses his ba- 

 lancing-pole ; and when the wind increases to a tem- 

 pest, and the bird can maintain the perch no longer, it 

 lets itself down by an oblique motion, with so much of 

 the wind under it, as prevents it from being beaten to 

 the earth, or injured by its fall. But to detail all the 

 varieties of muscular action and tendinous relief or 

 repose, with the different structures of feet, -wings, and 

 necks, which come into play in this one species of 

 action, although it is one of the most simple branches 

 of the subject, would fill volumes. 



The subject, however, not only admits of, but points 

 clearly at, one very general and important conclusion, 

 namely, that in all these adaptations, perfect and beau- 

 tiful as they are, the bird profits not a jot, and proceeds 

 not in the least, by what we call experience. And 

 even we, fond as we are of taking credit to ourselves 

 for plan and wisdom, find enough in the action of our 



animal frame to convince us that that action depends 

 upon principles more stable, and is directed by wisdom 

 more profound, than any to which we can rationally lay 

 claim. 



Now if in ourselves, and in the execution of those 

 works of art which are the applications of scientific 

 principles, we find that knowledge and manual dex- 

 terity are wholly different in their causes and means 

 of acquirement, and that the chain by which the dex- 

 terity is arrived at can be followed downward un- 

 broken, to the involuntary respiration and circulation 

 during sleep, or to the balancing of the sleeping bird 

 upon its perch, we must see clearly that the actions of 

 animals, however complicated or curious, and our own 

 action, in so far as that is animal, are the results of 

 material principles, or rather they are the results cf 

 certain arrangements or organisations of matter ; 

 that the laws or principles by which those actions are 

 produced are not properties of matter considered 

 abstractedly, or (so to speak) as " the stuff of which 

 animals are made," but principles resulting from the 

 organisation, and from that only ; that they do not 

 arise from any property which matter itself possesses 

 in its ordinary combinations and arrangements, but 

 that (though it may in some cases be minute beyond 

 our powers of observation,) there is always a distinct 

 ACT OF ORGANISATION before a new organised being 

 can exist ; that though, in our estimation, some of 

 them appear simple and others complicated, some 

 involuntary and others voluntary, yet they are all 

 equally simple and equally certain, never occurring but 

 under the circumstances which accord with their 

 occurrence, and never absent when those circumstances 

 take place ; that they are in perfect accordance with 

 all the laws of matter, and have their origin, their 

 growth, their decay, and their extinction, of creation 

 itself, and neither require nor admit of being separated, 

 though, as they depend upon combinations, it follows 

 that, in as far as we can alter the combinations, we can 

 change the result. 



This view of the matter and though it is not the 

 usual it is the only correct one the only one which 

 will carry us, without nonsense in philosophy and infi- 

 delity in religion (twin progeny of the same narrow- 

 minded ignorance) fairly through the analysis, from 

 the eye of the eagle, the proboscis of the elephant, the 

 human hand, or whatever else may be considered as 

 the perfection of organisation, to the primary atom, in 

 which gravitation itself is too minute for our observa- 

 tion, mightily enhances the value of animal action. 

 It lets us see that the whole of animated nature is in 

 our power, and that we may, according to the extent 

 of our knowledge, either enlist it directly in our ser- 

 vice, or copy it as a model, in so far as that which 

 has life can be imitated in that which has not. 



Some account of the more obvious kinds of ac- 

 tion in progressive motion will be found in the arti- 

 cles CREEPING, WALKING, FLYIN, and SWIMMING ; 

 and some notice of the more peculiar ones, especially 

 those of the invertebrated animals, in which they 

 appear to us most singular, from having the least simi- 

 larity to our own actions, will be found in the accounts 

 of the animals by which they are displayed. The 

 other branch of the general question, namely, the 

 means that must be adopted in turning the action of 

 animals to useful purposes, will be found slightly 

 noticed in the article AFFECTIONS OF ANIMALS. 



ACULEUS. A prickle attached to the bark, and 

 coming off along with it. It is unconnected ith th 



