KAYE AND JORDAN-LLOYD [1924] in an investigation of the swelling of fibrous tissue showed that single teased-out collagen fibres altered in length and breadth when treated in solutions of acids and alkalis. In that work single fibrebundles were obtained and the length and breadth were determined under the microscope by means of an eyepiece micrometer. The fibre-bundles were then treated with various reagents and the fibre-bundle re-measured. This method of observation is, however, extremely tedious and it is complicated by the great difficulty of measuring the breadth of the fibre-bundle, since this can vary to a very marked degree along the length of the bundle. This trouble becomes almost insurmountable when the fibre-bundles are swollen in acid solution, since there is a large amount of distortion and any attempt to express the results numerically leads to large errors.It was also shown that the swelling of hides and skins in the various liquors was dependent on the degree to which the hide fibres had been freed from each other. Thus the increase in volume of hide powder was of the same order as that of gelatin, while in the cases of pieces of hide and skin the percentage increase, although running parallel with that of hide powder, was very much smaller. The obvious difference between hide, as such, and hide powder is that in the former the individual fibres are not free to contract along their length nor are they free to increase in width since they are more or less closely interwoven. Thus the results obtained with loose fibre-bundles are not truly comparable with the effect produced on pieces of skin.It was therefore decided to endeavour to follow more accurately the effect of various solutions on single collagen fibre-bundles which were lightly held by their ends so that the effects observed would be more comparable with those taking place in the fibres when hides and skins are treated with different reagents. The first experiments were directed towards following the swelling of the fibres in acid liquors of known PH value.
DURING some recent experiments on the influence of various swelling agents on protein fibres it was noticed that, when treating hairs with concentrated solutions of sodium hydroxide in the cold, the cortex could be dissolved completely and the medulla, as far as microscopical appearance could tell, left intact. Human, horse and goat hairs could all be stripped of their cortex by this means, and it was therefore decided to make a sulphur analysis of the separated cortex and medulla. Although the absence of sulphur from the medulla is now generally accepted [King, 1933] and has been demonstrated by qualitative microchemical tests [Bekker and King, 1931] or inferred as a result of comparing data for medullated and non-medullated wool [Barritt and King, 1931], actual direct analysis of the two morphological parts of the hair shaft has not previously been recorded.Goat hair was chosen as the material for the work since a large supply was available. The hair had previously been washed with a large quantity of clean tap-water and dried and degreased with acetone. A qualitative test on white hairs made on short cut pieces of the hair showed that, by soaking overnight in a solution of sodium cyanide and then adding sodium nitroprusside, a pink colour
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