Lectures on clinical medicine / [John Hughes Bennett].

  • John Hughes Bennett
Date:
1850-1856]
Catalogue details

Licence: Public Domain Mark

Credit: Lectures on clinical medicine / [John Hughes Bennett]. Source: Wellcome Collection.

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    and are more or less compressed and changed in form. At length the vessel is completely distended with coloured corpuscles, the original form of which can no longer be discovered, and the tube appears to be filled with a homogeneous deep crimson fluid. This is congestion. If the morbid process continue, the vessel may burst, causing hemorrhage, or the serum and liquor sanguinis may transude through its walls, without rupture, into the surrounding texture. This is exudation. Fig. 1. Fig. 1 —Portion of web of the frog’s foot, viewed with a magnifying power of 250 diameters, after a drop of strong alcohol had been placed upon it. On the left of the figure the circulation is na¬ tural ; in its middle portion the column of blood is oscillating, and the corpuscles crowded together; on the right the circulation has stopped, and exudation has taken place. About the centre hemor¬ rhage has occurred, owing to laceration of a capillary vessel. II.— Theory of Exudation. It is of the utmost importance in pathological inquiries to sejjarate facts from theories. Our facts may be correct, although the conclusions derived from them are wrong. This proposition, however generally admitted, is sel¬ dom acted on; for in medical writings and statements we frequently find fact and hypothesis so mingled together, that it often requires considerable critical and analytical power to separate the one from the other. We are, however, in all cases, insensibly led to theorise—that is, to attempt an explanation of the phe¬ nomena observed, in order that we may derive from them some general prin¬ ciple for our guidance. Such speculation is always legitimate, so long as we consider opinions to be mere generalisations of known facts, and are ready to abandon them the moment other facts point them out to be erroneous. The phenomena of exudation, previously described, may easily be demonstrated—- they constitute the facts. Let us now examine how they have been attempted to be explained—in other words, what is the theory. 1. The contraction and dilatation of the capillaries is explicable, by suppos¬ ing them to be endowed with a power of contractility analogous to that existing in non-voluntary muscles. John Hunter thought they were muscu¬ lar, from the results of his observations and experiments; and they may be