Principles of human physiology / by William B. Carpenter.

  • William Benjamin Carpenter
Date:
1869
Catalogue details

Licence: Public Domain Mark

Credit: Principles of human physiology / by William B. Carpenter. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

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    under different circumstances, the former always increasing rapidly when the pabulum is abundant, and forming structures that are soft and easily disintegrated; whilst on the othe* hand, where the pabulum is deficient in quantity, the resulting tissues are of slow growth, dense con- sistence, and the formed material of which they are mainly composed resists disintegration and change. It is by no means necessary, how- ever, that the formed material should be dense or firm in its physical characters : it may be soft in consistence and soluble in water, as in the contents of the hepatic or renal cells. A very definite line of demarca- tion can in some instances be drawn between germinal matter and formed material by observing the effects of steeping the tissue in an ammoniated solution of carmine, which deeply dyes the former, whilst the latter, with certain exceptions, is only slightly stained by it. Carbon, Hydro- gen, Oxygen, and Nitrogen enter into the composition of every kind of germinal matter. These elements are united to form various proximate compounds, amongst which some form of Albuminous substance or Pro- teid, with a small proportion of fat, are invariably found to be present. 38. One of the most general forms of an ' elementary part' i3 that which is commonly known as a cell. This, in its complete and charac- teristic form, consists of a definite cell-wall enclosing cell-contents, and the latter, whatever may be their special nature, include a ' nucleus,' which has long been regarded as specially related to the formative activity of the cell. But there are many objections to this use of the term cell as indicating the elementary unit of structure. For there are a large number of cases in which there is no well-marked investing membrane to bodies which otherwise present the closest analogy to cells; the whole mass being composed of a minute segment of protoplasm or ger- minal matter, the exterior having undergone extremely slight, if any, consolidation. This is the case for example with the colourless corpus- cles of the blood, with granulation-cells and pus-corpuscles, with thej corpuscles of the ductless glands, and with cells generally in an early! stage of their development, the layer of formed material being here very! thin, and its separation from the germinal matter being far from com-j plete. In a more advanced condition we find the ' germinal matter' ] limited to a smaller proportion of the interior of the cell, so as to con- stitute what is known as its ' nucleus,' and this is surrounded by com-lt pletely differentiated ' formed material,' which may still have no definite* investment. Such appears to be the case with the red corpuscles of tha blood of oviparous vertebrata; for although these are commonly deJ scribed as perfect cells, having a cell-wall that contains the coloured! substance, no such cell-wall can be demonstrated; and the changes oJ form which these corpuscles can be made to undergo render its existence doubtful. Again, in Cartilage, we have an example in which thai ' nucleus' and ' cell-contents' are completely differentiated from tha 1 cell-wall;' but the ' cell-wall' itself cannot be separated from what hai been distinguished as the ' intercellular substance,' which is coramonlj regarded as the ' matrix' in which the true cartilage-cells are imbeddedp and it would appear from a study of the history of its development, thajt the ' intercellular substance,' ' cell-wall,' and ' cell-contents' are all to b*o regardedin the 1 i ght of layers of 'formed material' proceeding from thfl consolidation of the germinal matter originally present; this, on thj
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