64 GENERAL ANATOMY OF THE TISSUES. 



the other hand, in those forms which still present indications 

 of the original cells, a certain movement of the juices may still 

 take place. Elastic tissue is not known to be regenerated, but 

 new formations of it are not rare. 



The elastic tissue is rarely found in large masses, but it is 

 very frequently mixed with connective tissue, either in the 

 form of isolated fibres or of networks of various kinds. As 

 true elastic organs we may mention : 



a. The elastic ligaments, in which the tissue, with only a 

 slight admixture of connective tissue and hardly any vessels 

 and nerves, exists, so to speak, in a pure form. As such we 

 have the ligament a suhfiava of the vertebra?, the Uganientum 

 nucha, certain ligaments of the larynx, the stylo-hyoid liga- 

 ment, and the Uganientum suspensoriwn penis. 



b. The elastic membranes, which appear in the form either 

 of fibrous networks or of fenestrated membranes, and are found 

 in the walls of the vessels, especially in those of the arteries, 

 in the trachea and bronchia, and in the fascia superficialis. 



[in all the vertebrate classes the elastic tissue is found in 

 the same localities as in man, and in a few particular situations 

 besides, as in the ligaments of the cat's claw, in the alary 

 membrane of mammals, in the folds of the alary membrane 

 and in the lung sacs of birds. In the Invertebrata this tissue 

 appears to be rare, and it is not even certain that the elastic 

 ligaments which occur in them (as, for example, in bivalves), 

 agree anatomically and chemically with the elastic tissues of 

 the higher animals. 



Of the different parts belonging to the elastic tissues, the 

 so-called nucleus-fibres of Gerber are almost alone those whose 

 development has been examined. With regard to these, 

 Heule's view, that they arise by the coalescence of elongated 

 nuclei, was almost universally received, until lately Yirchow 

 and Donders nearly contemporaneously brought forward another 

 conception. Both these authors proceed from the investi- 

 gation of the connective tissue, and show that what in it have 

 been held to be elongated, isolated, or more or less coalesced 

 nuclei, are nothing more than fusiform or stellate cells, with 

 fine processes, which closely surround a generally elongated 

 nucleus, and are partly united into fibres or networks. With 



