The nervous system.

Date:
1882
Catalogue details

Licence: Public Domain Mark

Credit: The nervous system. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    posed are two in number, nerve-cells and nerve-fibres. There are indeed certain accessory parts that are always found in the nerve-centres, and in the nerve-fibres when these are massed together to form cords of a certain size ; but such parts must be regarded as incidental, and not as essential tissues. Thus it is requisite that both the nerve- cells and nerve-fibres should receive a sufficient quantity of nourishment and of oxygen, without which there can be no sustained activity; hence they are supplied by channels containing blood, the cells freely, the fibres more sparingly, and by a beautiful provision the same means thai minister to the oxidation and support of these tissues are subservient to the removal of the waste products of their action, which, if allowed to accumulate, would rapidly impair and ultimately abolish their activity. At the terminations of the nerves, again, certain peculiar organs are found which are fitted for the performance of special duties, and which differ in the case of each special sense: the terminal apparatus of the nerve distributed to the eye, for example, differing from that of the ear, and this again from the terminal apparatus of the nerves supplying the skin and the tongue. Such differences in the structure of the terminal organs are not present in the lower animals, and are only gradually superadded to, or differentiated from, the fundamental parts with the in- creasing complexity of the particular organs in question.