First report of the trypanosomiasis expedition to Senegambia (1902) of the Liverpool School of Tropical Medicine and Medical Parasitology / by J. Everett Dutton and John L. Todd ; with notes by H.E. Annett and an appendix by F. V. Theopold.

  • Dutton, Joseph Everett, 1876-1905.
Date:
1903
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Licence: In copyright

Credit: First report of the trypanosomiasis expedition to Senegambia (1902) of the Liverpool School of Tropical Medicine and Medical Parasitology / by J. Everett Dutton and John L. Todd ; with notes by H.E. Annett and an appendix by F. V. Theopold. Source: Wellcome Collection.

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    by Ehrlich* present no difficulty. It is in the estimation of the non-granular, mononuclear elements that there is a lack of uniformity. The criteria by which various observers decide exactly to what class a doubtful cell belongs are not always the same. Although there are two, or perhaps three, well-marked ‘types ’ of mononuclear leucocytes, forms intermediate between them may occur. There is no definite characteristic by which such intermediate forms may be classified ; and in differential counts, as often presented, the personal equation is a regrettable factor. It is in an effort to avoid this personal error, and to present our work in a form which will have areal clinical value, that we have grouped our mononuclear elements in the manner here described. The deeply basophile lymphocyte of about the same size as a red cell, with deeply staining cytoplasm and central, relatively large, nucleus is a constant, easily recognizable type. It must be remembered that, though forms are often seen whose protoplasm is not more basophile than their nuclei, yet these cells possess every other characteristic of small lymphocytes, and as such they must be classified. A study of a sufficient number of films will lead from these small forms, by insensible gradations, through a long series of mononuclear cells to a type of leucocyte possessing all the characteristics of a ‘ large mononuclear.’ The typical large mononuclear leucocyte, as described by Ehrlich Joe. cit.), occurs in normal blood in very small numbers (one per cent.) and is also a constant easily recognizable form. It is a huge cell, two to three times the size of a red cell, and possessing a relatively large amount of usually palely staining cytoplasm and an oval eccentrically placed nucleus. The cytoplasm is finely, the nucleus coarsely, reticulated.t Between these two extremes there is an intermediate group of cells possessing characteristics which do not conform to those of either division. Many observers, however, do not strictly hold to Ehrlich’s definition of a ‘ large mononuclear leucocyte,’ but classify under this head almost any cell which is slightly larger than a lymphocyte, possessing at the same time the staining reactions, structure, and often bean-shaped nucleus of a ‘large mononuclear.’ By so doing they avoid a complex classification. It is the difficulty of determining exactly what combination of properties is sufficient to place members of this large unclassified group into either of the two main divisions which has produced a third class ‘ large lymphocyte.’ The nuclei of any of these mononuclear cells may be ‘incurved,’ ‘ horseshoe shaped,’ or even sub-divided. Cells of the small lymphocyte type with irregular nuclei (rarely o-5 per cent, in normal blood) are classified as lymphocytes. Cells of the large mononuclear type * Ehrlich und Lazarus. Die Anaemic, Wien, 1898. -j- Ewing, Clinical Pathology of the blood, 1901.