ELASTIC TISSUE. 49 



ELASTIC TISSUE. 



THE elementary fibres of this tissue are somewhat extensively 

 distributed in the animal organism, although they seldom occur in 

 sufficiently large quantities to form special organs ; they occur, for 

 instance, in the yellow elastic ligaments (the ligamenta flava of the 

 vertebral column, the inferior vocal cords, the ligamentum nuchee 

 of mammals, the elastic ligaments of the claws of animals of the 

 Felidse, and the hinge-ligament of bivalves). We meet with larger 

 groups of elastic fibres connected into membrane-like sheaths in the 

 fascia lata, and in the ntiiddle coat of the arteries and veins. Smaller 

 accumulations of elastic fibres also occur in many other parts, as 

 for instance, in the corium, and under the mucous membrane, more 

 especially in the pharynx, the pylorus, the caecum, &c. We need 

 only observe here that the elementary fibres of this kind are met 

 with under different forms of grouping, either in wide-meshed or 

 very intricately formed nets having hook-like indentations; as 

 fenestrated membranes exhibiting tolerably large intervals, and 

 resembling an anastomising vascular network ; or lastly, only as 

 bundles or fibres twining around other tissues in a spiral manner. 

 It is at the present day assumed by most histologists, that these 

 true elastic fibres, which occur in the form of flat, rather broad, 

 somewhat brittle, and much ramifying bands, are perfectly identi- 

 cal with those far narrower, spirally coiled nuclear fibres, which 

 are often studded with nuclei, and are invariably present in con- 

 nective tissue; and they have arrived at this conclusion, partly from 

 watching the development of these tissues, and partly because the 

 slightest transition from one form to the other admits of recogni- 

 tion ; moreover, the chemical reactions of the two forms do not 

 indicate any difference between them. 



The elastic fibres never occur independently of other histological 

 elements, however much they may predominate; most commonly 

 they are found intermixed with the fibres of connective tissue, very 

 frequently also with smooth muscular fibres (Kolliker's fibre-cells),* 

 as in the middle coat of the arteries. Close to the fenestrated coat, 

 the elastic fibres, intermingling in part with nuclear fibres, merge 

 into the so-called contractile tissue, which is principally formed of 

 these smooth fibres, to which they undoubtedly owe the property 

 of contracting under the action of cold (Schwannf) or magnetic 



* Zeitschr. f. wiss. Zool. Bd. 1, 8. 78-82. 



t M tiller's Handb. der Physiologie. Bd. 1, S. 170, u. Bd. 2, S. 20 [or 

 English Translation, Vol. 1, 2nd edition, p. 218, and Vol. 2, p. 876.] 

 VOL. III. E 



