Further researches on the grey substance of the spinal cord / by J. Lockhart Clarke.

  • Jacob Augustus Lockhart Clarke
Date:
1859
Catalogue details

Licence: Public Domain Mark

Credit: Further researches on the grey substance of the spinal cord / by J. Lockhart Clarke. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    -J 460 ]\£R. J. L. CLAEKE ON THE GEET SUBSTANCE OF THE SPINAL COED. ceed with him; “ the preparation became only partially clear, and the ganglionic cells, from which the fat seemed to be removed, were rendered indistinct*.” It is perfectly clear that he had not snfficient practice in the process. He says again, in speaking of Lenhossek, “ he follows Clarke’s method with turpentine, Avhich, according to my expe- rience^ cannot lead to correct results, as the spinal marrow is too much altered by that agent f.” After criticising every other method, he describes his own, which consists in the use of concentrated chloride of calcium, and which, according to his experience, “ deserves to be preferred to all the others.” But now we find that he has abandoned it, and adopted my method in conjunction with the colouring process recommended by Gerlach ; for in a supplementary paragraph to the English translation which has just been issued by the Sydenham Society (1859), he states that after some trials he finds this mode of making preparations the most satisfactory, and in many respects still better than with chloride of calcium. The section, after having been coloured with solution of carmine and washed in spirit, is laid in a watch-glass and allowed to dry a little, after which, “ a couple of di'ops of spirit of turpentine are added. If it is now left for twenty-four or forty-eight hours without a covering glass, but protected from the dust, the spirit evaporates, and the object becomes perfectly clear. It is now covered with Canada balsam and a glass J.” The colouring with carmine is often very useful, but I think it rather interferes with the sharpness of the fibres. I have long used, occa- sionally, a colouring fluid kno\^m to painters and wood-stainers by the name of archel. ’When carmine is used, the solution should be previously filtered, otherwise a deposit or crust is apt to form on the object; and for the same reason, the section, after having been coloured, should be washed in water before it is placed in the spirit, which readily precipitates the carmine. Stilling has given a full, but somewhat inconsistent and incorrect criticism on my method. He concludes by saying, “’While it is allowed that by the employment of Clarke’s method many truths indeed in reference to the minute structure of the spinal cord may be brought to light, and that Clarke’s labours must be said to be quite trust- worthy (recht anerkennenswerthe), it must nevertheless be observed that the condition of certain textures, such as the elementary structure of the primitive nerve-fibres and the nerve-cells, are so altered by it, that this method in many respects must be con- sidered as an obstacle to the more exact kind of investigation Now, although I am not so blindly prejudiced as to maintain that preparations made by this method are in every respect perfect, I do maintain that it produces but little alteration from the natural appearance of the nerve-cells, and that almost the only structure that appears to suffer more than from chromic acid alone is the white sub- stance of the nerve-fibre; and even this may be perfectly preserved if the medulla is placed first in a weak solution of chromic acid and then in a solution which is much stronger. Fig. I, Plate XIX. was drawn from a preparation made in this way, and of * Translation of Sydenham Society, 1859, p. 30. t Ibid. p. 28.