A manual of physiology : including physiological anatomy / by William B. Carpenter.

  • William Benjamin Carpenter
Date:
1856
Catalogue details

Licence: Public Domain Mark

Credit: A manual of physiology : including physiological anatomy / by William B. Carpenter. Source: Wellcome Collection.

    52/690 (page 20)
    of this compound is mucli less dependent upon the nutrient materials which are supplied to the cell, than upon the original inherent powers of the cell itself, derived from its germ. Thus we find that the ' red snow ' and ' gory dew' invariably form a peculiar red secretion ; and that they will only grow where they can obtain, from the air and moisture around, the elements of that secretion. Again, the ' yeast-plant' invariably forms a secretion analogous to animal albumen ; and it will only grow in a fluid which supplies it with the materials of that substance. Hence the 'red snow' would not grow in a fermentible saccharine fluid ; nor would the * yeast plant' vegetate on damp cold surfaces. Yet there is little diiference, if any, between their cell-walls, in regard to chemical composition,—So, also, we shall find hereafter that one set of cells in the animal body will draw into themselves, during the process of growth, the elements of bile ; anothei-, the elements of milk ; another, fatty matter ; and so on : the peculiar endowments of each being derived from their several germs, which seem to have an attraction for these substances respectively, and which thus draw them together ; whilst the cell-wall appears to have a uniform com- position in all instances. 32, The term Secretion or setting apart, is commonly applied to this operation, to distinguish it from Nutrition or growth ; but it is obvious from what has now been stated, that the act of secretion is in reality the increase or growth of the cell-contents, just as the process of enlargement is the increase or growth of the cell-wall; and that the two together make up the whole process of Nutrition, which cannot be properly understood, unless both are taken into account. It is to be remembered, however, that the contents of the cell may not be destined to undergo organization ; indeed we shall find hereafter, that the main use of certain cells is to draw-off from the circulating fluid such materials as are incapable of organization; and the operation may be so far attributed, therefore, to the agency of Chemical forces. But we shall find that, in other instances, the cell-contents cm'C destined to undergo organization, and this either within the parent-cell, or after they leave it ; here, then, we must recognize a distinct vitalizing agency, as exerted by the cell upon its contents. 33, This organizing or vitalizing influence must be exerted upon a certain portion of the contents of every cell that is capable of reproducing itself; for it is in this manner that those germs are produced, in which all the wonderful properties are inherent, that are destined to manifest themselves, when they are set free from the parent-cell. This power of Reproduction is one of those wdiich most remarkably distinguishes the living being ; and we shall find that, in the highest Animal, as in the humblest Plant, it essen- tially consists in the preparation of a cell-germ, which, when set free, gradually developes itself into a structure like that from