. Des soirées au microscope : ou, de recherches parmi les organes et minuter formes de vie animale . Microscopie ; zoologie ; microscopes. HAIES, de plumes et d'écailles. 5 (2) une substance fibreuse, s'étendant de l'ampoule au point des cheveux. En trempant les cheveux en acide sulfurique chaud, cette substance fibreuse se constitue en un immense nombre de cellules très longue, pointue à chaque extrémité, et pressé par la pression mutuelle en diverses formes angulaires. " Un cheveu humain, d'un dixième d'une ligne d'épaisseur,* a environ 250 dans sa simple de fibrilles de diamètre, et d'environ 50 000 dans l'ensemble de son calibre : afin que ces

• Contributeur: The Book Worm
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. Evenings at the microscope : or, Researches among the minuter organs and forms of animal life . Zoology; Microscopy; Microscopes. HAIES, FEATHERS, AND SCALES. 5 (2) a fibrous substance, extending from the bulb to the point of the hair. By soaking the hair in hot sulphuric acid, this fibrous substance resolves itself into an immense number of very long cells, pointed at each end, and squeezed by mutual pressure into various angular forms. " A human hair, of one-tenth of a line in thickness, * has about 250 fibrils in its mere diameter, and about 50, 000 in its entire calibre: so that these ultimate fibrils are finer than those of almost any other known tissue, from the great elongation and narrowing of their constituent cells as they are drawn out into the shaft of the hair during growth ; and hence the expanded bulb of the hair, where the cells are yet spherical and soft."+ (3) Eunning through the very centre of the fibrous portion may be sometimes discerned a dark slender line, which is a sort of pith (medulla) composed of minute roundish cells, filled with air, and arranged in two or three rows. J. HOG'S BRISTLES. The bristles of the Hog bear much resemblance to the human hair. On this slide is one (a), which you perceive * Thia is nearly thrice as great as the diameter I have given above, which is the result of several careful admeasurements of different hairs, taken from childhood and adult age. t Grant, " Outl. Comp. Anat., " 647. J " Xhe cortical (or bark-like) substance has different colour, accord- ing to the colour of the hair; generally, the colour is diffused through its whole mass; less frequently, the colour depends on granular pigment scattered through its substance in small masses. The cortical substance. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Gosse

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