62 Mk. Crum on a Peculiar Fibre of Cotton incapable of being Dyed. 



originally cylindrical, but which collapses in drying. It has then the 

 appearance of two small tubes joined together, so that a transverse section 

 of the filament resembles in some degree a figure of 8. Until full matu- 

 rity, the cylinder is distended with water, in which bubbles of air are often 

 distinguishable. 



On placing a few of the fibres of the coton mort under the microscope, 

 I found them to consist of very thin and remarkably transparent blades, 

 some of which are marked or spotted, while others are so clear as to be 

 almost invisible, except at the edges. These fibres are readily distin- 

 guished from those of ordinary cotton by their perfect flatness, without the 

 vestige of a cavity, even at the sides, and by their uniform as well as great 

 transparency. They are often broader, too, than the usual fibre, and they 

 show numerous folds, both longitudinal and transverse, but they are never 

 twisted into the cork-screw form of the ordinary fibre. 



It occurred to me that cotton of this description might be detected 

 among the wool as it is imported. I searched accordingly for any portions 

 that had a difierent appearance from the rest, and having collected and 

 examined them, I found one sort whose filaments had exactly the appear- 

 ance, under the microscope, of the coton mort in the pattern of Mr. 

 Koechlin. It occurs in the form of a small matted tuft of a shining silky 

 lustre, and usually contains in its centre the fragment of a seed, or perhaps 

 an abortive seed. It consists of short fibres, having little tenacity. 

 Specimens of it are found in abundance among the motes or hard portions, 

 called droppings, rejected by the picking machine in the preparation for 

 spinning. Small tufts of it, however, do occasionally pass the sifting 

 process of the picking machine, and then, their fibres being too short to be 

 teazed out in the carding engine, or drawn into threads in the subsequent 

 operations of cotton spinning, remain as minute lumps or knots upon the 

 threads of better wool. 



Although the microscopic appearance of the fibre in question is that of 

 a flat single blade, the cellular character of the tissue scarcely admits of 

 such a formation. We must rather suppose that like the healthy unripe 

 cotton fibre, it was originally an elongated cell or tube filled with liquid 

 — that the seed around which it began to grow had died soon after its 

 formation, while the fibres which clothed it were yet soft and pliable, and 

 that the flattening, and perhaps growing together of the sides of the tube 

 was occasioned by the pressure from the increasing crop of cotton attached 

 to the numerous other seeds confined in the same pod. 



To explain the bearing of this peculiar structure upon the question, 

 whether cotton-wool and colouring matters form together a true chemical 

 compound, or are held together by a merely mechanical power, I must 

 quote a passage from a memoir on this subject which I read to the 

 Philosophical Society six years ago, and refer to the memoir itself for 

 additional illustrations. 



" In many of the operations of dyeing and calico-printing, the mineral 

 basis of the colour is applied to the cotton in a state of solution in a 



