Imbedding in elder pith, for cutting sections / by C.H. Golding Bird.

  • Cuthbert Hilton Golding-Bird
Date:
[between 1880 and 1889?]
Catalogue details

Licence: Public Domain Mark

Credit: Imbedding in elder pith, for cutting sections / by C.H. Golding Bird. 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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    only is often enough, especially in the case of chromic acid specimens that have undergone a full degree of hardening. Besides causing it to swell, the moistening of the pith takes away that extreme brittleness that characterises it in the dry state, and which, by causing it to break from the specimen embedded, would effectually frustrate any attempts to obtain a good section; for this reason pith, even if held in the fingers only, should be previously moistened. As in cutting wax specimens, the razor should be dipped in spirit. To those who have never tried it this process will probably at first sight offer several objections; these, however, I hope to show may not only be overcome, but that real advantages are to be found in it. The pressure exerted upon the specimen by the swelling pith naturally first suggests itself as the principal drawback. In answer I can only say that if the tissue be hardened in the usual manner and to the usual degree, nothing is to be feared on this score ; I have both used it and seen it used with very many varieties of tissue, and never found it exert a pressure that in any way was productive of harm, and this remark applies even to such structures as spinal cord, provided they have previously undergone, as stated above, the usual amount of hardening. Should it be feared in any one case that pressure, however slight, might do some injury, the specimen can, previously be covered with a thin coating of wax or paraffin, and then fitted into the pith. The chance of the pith revolving in the microtome like wax has already been alluded to; this in- convenience never occurs, the friction offered by the rough pith being sufficient to prevent it. To the vegetable histologist pith is an invaluable medium; for wax et hoc genus omne are almost out of the question when it comes to cutting sections of leaves and the like; while, further, the pith is far less likely to blunt the razor, and is more easily moulded than carrot, to which many resort for a similar purpose. It may further be urged that pith always involves the use of the microtome ; and so it certainly does : for when simply held in the fingers, though capital results may be obtained, I fully admit that imbedding in wax is preferable if the time for it can be spared. The question, therefore, of pith versus wax is one chiefly of time and of comparison, and though many microscopists seem to have an innate hatred of microtomes, I ask whether it is better to adopt a process involving mechanical aid, but that costs no time to speak of, and next to no trouble, or one in which mechanical aid without special adaptation cannot, even if required, be