The chemistry of nerve-degeneration / by F.W. Mott and W.D. Halliburton.
- Frederick Walker Mott
- Date:
- 1901
Licence: In copyright
Credit: The chemistry of nerve-degeneration / by F.W. Mott and W.D. Halliburton. 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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![blood yield wholly negative results. The largest yield of choline in a normal animal which we have met with was in a yonng kitten, and doubtless in young animals the myelinisation of the nerve fibres which is taking })lace ini])hes more active metabolism of the lecithin than in adult animals. The general jhan of our work has been (1) to examine the blood in various diseases of the nervous system in man ; (2) to examine tlie blood in animals in wliicli degeneration of the nerves has been made to occui' by section of large nerves like the sciatics ; (3) in these animals we have examined the nerves themselves in various stages of degeneration; this examination has been partly microscopic and partly cliemical, and we have sought to correlate the two sets of changes, and in j)articular have endea- voured to ascertain the chemical meaning of the Marchi reaction, which is the method principahy used to-day for the microscopic detection of degeneration in nerve fibres. Before passing on to consider our experiments, observations, and results in detail, it may be well at this point to allude to the composition of lecithin, and to the main features of the Marchi reaction. Lecithin, the main constituent of the medullary sheath, differs from ordinary fats in containing two additional elements, namely nitrogen and phosphorus. An ordinary fat on decomposition breaks up into glycerin and fatty acid. Lecithin under similar circumstances yields glycerin, fatty acid, phosphoric acid, and a base called choline (C.H.^NO,). _ We have in our work endeavoured to follow the history of lecithin disintegration, not only in regard to the nitrogen it contains (the choline radicle), but also in respect of its phosphorus. It is probable that in the body lecithin is not present in the free state, Imt in combination with a cerebrin or cerebrins to form a still more complex substance cahed protagon. The Marchi reaction consists in placing small pieces of nervous tissue in a mixture of osmic acid and Muller’s fluid, after previous hardening in MiiLLER’s fluid. Under these circumstances healthy nerve fibres are not stained, but degenerated nerve fibres are stained an intense black. In the later stages of degeneration, when the fatty products of the decomposition of the fibres have been absorbed, this black staining is naturally no longer observable. It is important also to observe that ordinary neutral fats, such as are contained in adipose tissue, give the Marchi reaction. It was knowledge of this fact that led us in part to the present investigation, and our expectation has been fully confirmed that the cause of the Marchi reaction in degenerated nerve fibres is the replacement of the phosphorised fat by non-phosphorised fat. Before the commencement of our joint work, one of us (F. W. M.)* had made some preliminary experiments in this direction, which were continued in conjunction with Dr. Barratt. t Spinal cords on one side of which degeneration had occurred, due to * Clifford Allbutt, ‘ System of Medicine,’ vol. 1, “ Pathology of Nutrition.”](https://iiif.wellcomecollection.org/image/b22392683_0007.jp2/full/800%2C/0/default.jpg)
