A treatise on the blood, inflammation, and gun-shot wounds / by John Hunter ; with notes by James F. Palmer.

  • John Hunter
Date:
1840
Catalogue details

Licence: Public Domain Mark

Credit: A treatise on the blood, inflammation, and gun-shot wounds / by John Hunter ; with notes by James F. Palmer. 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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    When an old opinion is partly exploded and a new one brought forward, it becomes only necessary to see how far the new one is just; because if it be not proved, we must revert to the old opinion again, or to some other. Mr. Hewson has been at great pains to examine the blood in the microscope, and has given us figures of the different shapes of those globules [Phil. Trans. 1773, p. 303]; but there is reason to think he may have been deceived in the manner I have just mentioned. The red globules are always nearly of the same size in the same animal, and when in the serum do not run into one another as the oil does when divided into small globules in water. This form, therefore, does not arise simply from their not uniting with the serum, but they have really a determined shape and size. This is similar to what is observed of the globules in milk; for milk being oily, its globules are not soluble in water; neither do they consist of such pure oil as to run into each other; nor will they dissolve in oil. I suspect, therefore, that they are regular bodies, so that two of them could not unite and form one. What this property in the red part is I do not know, for it has something like the nature of a solid body; yet the particles seem not to have the properties of a solid, for to the touch they yield no feeling of solidity. When circulating in the vessels they may be seen to assume elliptical forms, adapting themselves to the size of the vessels; they must therefore be a fluid, with an attraction to themselves while in the serum which forms them into round glo- bules, yet without the power of uniting with one another, which may arise from their central attraction extending no further than their own circumference. If they are found, however, of an oval figure in some animals, as authors have described, that circum- stance would rather oppose the idea of their being a fluid having a central attraction ; but this is probably an optical deception. Whatever their shape is, I should suppose it to be always the same in the same animals, and indeed in all animals, as it must depend upon a fixed principle in the globule itself. Hence the less credit is to be given to those who have described the globules as being of an oval figure in some animals; for they have also described them as being of different and strange shapes even in the same animal.* * I am led to believe that we may be deceived by the appearances viewed through a magnifying glass; for although objects large enough to be seen by the naked eye are the same when viewed through a magnifying glass which can only magnify in a small degree, yet as the naked eye, when viewing an object rather too small for it, is not to be trusted, it is much less to be depended upon when viewing an object infinitely smaller brought to the same magnitude by a glass. In such a situation, respecting our eye, all the relative objects by which the eye, from habit, judges with more nicety of the object itself, are cut off! The eye has likewise a power of varying its forms, adapting it to the different distances of the parts of an object within its compass, making the object always a whole; but a magnifying glass has no such power. For instance, in viewing a spherical body, a magnifying glass must be made to vary its position, and bring in succession the different parts of the hemisphere into so many focal points, every part separate not having the same relative effect on our organ of vision as when they are all