Licence: Public Domain Mark
Credit: The nervous system and its functions / by Herbert Mayo. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
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![XXI. In connexion with tlie preceding anato- mical law, [it is to be remarked that] an influence may be propagated from tbe sen- tient nerves of a part to their correspondent nerves of motion, through the intervention of that part alone of tbe nervous centre, to which they are mutually attached. Thus, in vertebral animals, in which alone the fact is questionable, when the spinal cord has been divided in two places, an injury of the skin of either region is followed by a distinct muscular action of that part. Again, if the brain be quickly removed from a decapitated pigeon, excepting only the fore part of the crura cerebri, together with the tubercles and the second and third nerves, on pinching the second nerve the iris contracts. This law I have likewise here enunciated in the same terms as in my Anatomical and Physiological Commentaries, published in 1823. About the same time, I gave greater pre- cision to the experiment above described on the head of the decapitated pigeon, thus. Re- peating it, I further divided the optic nerves. So that nothing was left as a means of com- munication with the eyeballs but the third](https://iiif.wellcomecollection.org/image/b21941841_0060.jp2/full/800%2C/0/default.jpg)
