TISSUES, ORGANS, AND SYSTEMS. 81 



Literature. Meckauer, " De penitiori cartilaginum structura Diss.," 

 Vratisl. 1836; J. Muller, in "Poggendorfs Annalen," 1836, p. 293; 

 Rathke, in Froriep's "Notizen," 1847, p. 306; A. Bergmarin, "De car- 

 tilaginibus Disq. micr.," Mitaviae, 1850. [Leidy, "On the structure of 

 articular cartilage," American Journal of Med. Sci. April, 1849.] 



23. Elastic Tissue.* The elements of elastic tissue are cylindrical 

 or band-like fibres, with dark contours, which vary in their diameter 

 from immeasurable fineness up to a thickness of 0-003, and even 0-005 

 of a line (in animals even to as much as 0-008 of a line), and when they 

 are present in quantity, exhibit a yellowish color. These so-called 

 elastic fibres are, when perfectly formed, quite solid, but may subse- 

 quently acquire little cavities in particular spots ; and these, in one 

 animal, the Giraffe (Quekett, "Histological Catalogue," i.), are so regu- 

 lar, that the fibres present a pretty transversely striated appear- 

 ance. The margins of the elastic fibres are in general quite rectilinear, 

 but in some rare cases appear to be notched and even, as Virchovv saw 

 them, in newly-developed tissues, beset with a great number of shorter 

 and longer pointed processes. Hitherto the elastic fibres have been 

 separated from the nucleus-fibres : since, however, the latter are dis- 



Fig. 21. 



tinguished from the former in nothing but their diameter ; furthermore, 

 as all elastic fibres are originally as fine as nucleus-fibres ; and since, 

 finally, the latter are not formed of nuclei alone, it will be better wholly 

 to suppress the name of nucleus-fibres, and to divide the v elastic fibres simply 

 into finer and coarser. The elastic fibres are found either isolated as 

 longer or shorter fibres, which may be straight or wind spirally round 

 other parts (bundles of connective tissue, nerves), and in this case they 

 are commonly of the finer kind ; or by the anastomosis of fibres of dif- 

 ferent sizes, a so-called fibrous elastic network is formed, which is some- 



FiG. 21. Portion of a human epiglottis; magnified 3 r O diameters. 



FIG. 22. Elastic network from the tunica media of the pulmonary artery of a horse, 

 with lacuna- in the fibre ; magnified 350 diameters. 



* [Yellow fibrous tissues DaO.] 



