A manual of surgery for students and practitioners / by William Rose and Albert Carless.

  • William Rose
Date:
1900
Catalogue details

Licence: Public Domain Mark

Credit: A manual of surgery for students and practitioners / by William Rose and Albert Carless. Source: Wellcome Collection.

    35/1254 (page 17)
    the living leucocyte (Fig. 3), although opponents to this theory suggest that it is only dead or dying organisms which are dealt with in this way ; whilst it is also a well-known fact that the presence of organisms within cells is no absolute evidence of phagocytosis, since the latter may be invaded and finally destroyed by the bacteria, as in leprosy and gonorrhoea. As an important outcome of this doctrine has arisen the idea of Chemiotaxis, a term introduced to indicate an attractive or repulsive power exercised upon the leucocytes by foreign bodies or various chemical substances, particularly those dependent on bacterial activity. By positive chemiotaxis is meant the attraction whereby leucocytes are gathered towards any tissues in which bacteria have commenced to develop ; the organisms or their products seem to have a power of causing active diapedesis and exudation of plasma, as a result of which the spread of the microbic invasion is more likely to be limited, and the inflammation thus caused is Fig. 3.—Phagocytosis. (Tillmanns.) In the first figure the rod-shaped organism is being absorbed or swallowed by' the phagocyte ; in the second it is incorporated in its body, and in the third it is being disintegrated. protective rather than destructive. Positive chemiotaxis is to be looked on, then, as one of Nature’s defences against an active and vigorous microbic attack. That it occurs cannot be questioned, though no explanation as to its origin or nature is at present forthcoming. It must be noted, however, that its existence is no evidence in favour of Metchnikoff’s theory, since where leucocytes are collected, there is certain to be an increased effusion of plasma or serum. Negative chemiotaxis, on the other hand, is the term applied to a condition in which the leucocytes are apparently repelled by the organisms, probably on account of their virulent nature, though it is impossible to prove that any active repulsion exists. Both phenomena can be seen very well by inoculating the cornea of an animal with the Aspergillus niger, as was done by Leber; the spot of inoculation looks opaque and dull, owing to the development therein of the mycelium of the fungus, and the necrosis caused thereby ; around this is an area of clear corneal tissue which is necrotic, but free from leucocytes owing to negative chemiotaxis. Outside this, again, is a circle of infiltrated tissue, at first of a whitish-yellow colour, and finally breaking down into 2