just been said about the dark-coloured races blushing in an invisible manner.

The hypothesis which appears to me the most probable, though it may at first seem rash, is that attention closely directed to any part of the body tends to interfere with the ordinary and tonic contraction of the small arteries of that part. These vessels, in consequence, become at such times more or less relaxed, and are instantly filled with arterial blood. This tendency will have been much strengthened, if frequent attention has been paid during many generations to the same part, owing to nerve-force readily flowing along accustomed channels, and by the power of inheritance. Whenever we believe that others are depreciating or even considering our personal appearance, our attention is vividly directed to the outer and visible parts of our bodies; and of all such parts we are most sensitive about our faces, as no doubt has been the case during many past generations. Therefore, assuming for the moment that the capillary vessels can be acted on by close attention, those of the face will have become eminently susceptible. Through the force of association, the same effects will tend to follow whenever we think that others are considering or censuring our actions or character.

As the basis of this theory rests on mental attention having some power to influence the capillary circulation, it will be necessary to give a considerable body of details, bearing more or less directly on this subject. Several observers,[33] who from their wide experience and knowledge are eminently capable of forming a sound judgment, are convinced that attention or consciousness (which latter term Sir H. Holland thinks the more explicit) concentrated on almost any part of the body produces some direct physical effect on it. This applies to the movements of the involuntary muscles, and of the voluntary muscles when acting involuntarily,-- to the secretion of the glands,--to the activity of the senses and sensations,--and even to the nutrition of parts.

[32] On the authority of Lady Mary Wortley Montague; see Burgess, ibid. p. 43.

It is known that the involuntary movements of the heart are affected if close attention be paid to them. Gratiolet[34] gives the case of a man, who by continually watching and counting his own pulse, at last caused one beat out of every six to intermit. On the other hand, my father told me of a careful observer, who certainly had heart-disease and died from it, and who positively stated that his pulse was habitually irregular to an extreme degree; yet to his great disappointment it invariably became regular as soon as my father entered the room. Sir H. Holland remarks,[35] that "the effect upon the circulation of a part from the consciousness suddenly directed and fixed upon it, is often obvious and immediate." Professor Laycock, who has particularly attended to phenomena of this nature,[36] insists that "when the attention is directed to any portion of the body, innervation and circulation are excited locally, and the functional activity of that portion developed."

[33] In England, Sir H. Holland was, I believe, the first to consider the influence of mental attention on various parts of the body, in his `Medical Notes and Reflections,' 1839 p. 64. This essay, much enlarged, was reprinted by Sir H. Holland in his `Chapters on Mental Physiology,' 1858, p. 79, from which work I always quote. At nearly the same time, as well as subsequently, Prof. Laycock discussed the same subject: see `Edinburgh Medical and Surgical Journal,' 1839, July, pp. 17-22. Also his `Treatise on the Nervous Diseases of Women,' 1840, p. 110; and `Mind and Brain,' vol. ii. 1860, p. 327. Dr. Carpenter's views on mesmerism have a nearly similar bearing. The great physiologist Muller treated (`Elements of Physiology,' Eng. translat. vol. ii. pp. 937, 1085) of the influence of the attention on the senses. Sir J. Paget discusses the influence of the mind on the nutrition of parts, in his `Lectures on Surgical Pathology,' 1853, vol.

Charles Darwin

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