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This is the first reflex Post Date: Sun, 31 Aug 2008 20:22:55 +0000 A cat, even when deprived of its cerebral hemispheres, will in most cases land on its feet when thrown from a height. How is this managed? When the position of the otolithic organ in space is altered a definite reflex is evoked which brings about a contraction of the muscles in the neck, restoring the animal s head to the normal position. This is the first reflex. Autor of the post: Undefined Some, again, object Post Date: Sun, 31 Aug 2008 20:11:53 +0000 With the righting of the head a fresh reflex is evoked, and certain muscles of the trunk and limbs are brought into play, restoring the animal to the standing posture. This is the second reflex. Some, again, object to the identification of instincts with reflexes on this ground: instincts, they say, frequently depend upon the internal state of an organism. Autor of the post: Undefined Again, the same is true Post Date: Sun, 31 Aug 2008 19:59:09 +0000 For instance, a bird only builds its nest in the mating season. Or, to take a simpler case, when an animal is satiated with eating, then food has no longer any attraction and the animal leaves off eating. Again, the same is true of the sexual impulse. Autor of the post: Undefined " The intensity of any reflex Post Date: Sun, 31 Aug 2008 19:47:07 +0000 This depends on the age of the or ganism, and on the state of the reproductive glands; and a con siderable influence is exerted by hormones (the products of the glands of internal secretion) . But this dependence cannot be claimed as a peculiar property of "instincts." The intensity of any reflex, indeed its very presence, is dependent on the irritability of the centres, which in turn depends constantly on the physical and chemical properties of the blood (automatic stimulation of cen tres) and on the interaction of reflexes. Autor of the post: Undefined It follows from all Post Date: Sun, 31 Aug 2008 19:28:43 +0000 Last of all, it is sometimes held that whereas reflexes deter mine only the activities of single organs and tissues, instincts in volve the activity of the organism as a whole. We now know, how ever, from the recent investigations of Magnus and de Kleijn, that standing, walking and the maintenance of postural balance in general, are all nothing but reflexes. It follows from all this that instincts and reflexes are alike the inevitable responses of the organism to internal and external stimuli, and therefore we have no need to call by them by two different terms. Autor of the post: Undefined It is therefore of great Post Date: Sun, 31 Aug 2008 19:10:26 +0000 Reflex has the better claim of the two, in that it has been used from the very beginning with a strictly scientific connotation. The aggregate of reflexes constitutes the foundation of the nervous activities both of men and of animals. It is therefore of great importance to study in detail all the fundamental reiicxes of the organism. Autor of the post: Undefined Their classification under such headings Post Date: Sun, 31 Aug 2008 18:54:19 +0000 Up to the present, unfortunately, this is far from being accomplished, especially, as I have mentioned before, in the case of those reflexes which have been known vaguely as "in stincts." Our knowledge of these latter is very limited and frag mentary. Their classification under such headings as "alimentary "defensive," "sexual," "parental" and "social" instincts, is thor oughly inadequate. Autor of the post: Undefined It was evidently a very Post Date: Sun, 31 Aug 2008 18:35:37 +0000 Under each of these heads is assembled often a large number of individual reflexes. Some of these are quite un identified; some are confused with others; and many are still only partially appreciated, I can demonstrate from my own experience to what extent the subject remains inchoate and full of gaps In the course of the researches which I shall presently explain, we were completely at a loss on one occasion to iind any cause for the peculiar behaviour of an animal. It was evidently a very tractable dog, which soon became very friendly with us. Autor of the post: Undefined scratching at the floor, gnawing Post Date: Sun, 31 Aug 2008 18:18:15 +0000 We started off with a very simple experiment The dog was placed in a stand with loose loops round its legs, but so as to be quite comfortable and free to move a pace or two. Nothing more was done except to present the animal repeatedly with food at intervals of some minutes It stood quietly enough at first, and ate quite readily, but as time went on it became excited and struggled to get out of the stand, .scratching at the floor, gnawing the supports, and so on. Autor of the post: Undefined We tried out experimentally numerous Post Date: Sun, 31 Aug 2008 18:02:35 +0000 This ceaseless mus cular exertion was accompanied by breatlilessness and continuous salivation, which persisted at every experiment during several weeks, the animal getting worse and worse until it was no longer fitted for our researches. For a long time we remained purled over the unusual behaviour of this animal. We tried out experimentally numerous possible interpretations, but though we had had long experience with a great number of dogs in our laboratories we could not work out a satisfactory solution of this strange be haviour, until it occurred to us at last that it might be the expres sion of a special freedom reflex, and that the dog simply could not remain quiet when it was constrained in the stand. 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