64 HISTOLOGY. 



and to the fact that one can separate it into long white fibres 

 which are quite tough and strong. This tissue always contains 

 a small number of elastic fibres and various connective-tissue 

 cells. 



(d) Elastic connective tissue is the name given to a tissue 

 which is made up in large part of elastic fibrils. It is known also 

 as yellow elastic tissue, on account of its bright-yellow color 

 when it is seen in large quantities, as, e. y., in the ligamentum 

 nuchse of an ox, where the elastic fibres are so abundant that 

 white fibrils can hardly be distinguished among them. This 

 tissue may be a part of an organ (e. g., in the blood-vessels), or 

 it may make up a whole organ by itself, as in the ligamentum 

 nuchse and ligamentum intercrurale. The thickness of elastic 

 fibres varies considerably from a fraction of a ^ to more than 

 10 (JL. They often cross and form a network with meshes of 

 large size. The fibres have a considerable degree of elasticity, 

 and are usually cylindrical and arranged often in bands. If 

 such flat bands fuse with one another, there is formed an elastic 

 membrane, which may present small openings or windows, from 

 which is derived the name of the fenestrated membrane, which 

 is present in medium-sized arteries (see below). 



When elastic tissue is boiled in concentrated HC1, it disinte- 

 grates in such a way that the fibrils are partially dissolved. 

 According to Mall, the interior of the fibril dissolves first and 

 leaves a membrane intact. This is called the membrane of 

 Schwalbe. Sometimes, a fibrillar structure can be made out in 

 these membranes, indicating that they are probably made up 

 of more than one substance. The interior of the fibre stains 

 intensely with magenta, while the membrane remains uncolored. 



The fenestrated membrane of Henle may be isolated, accord- 

 ing to Mall, by boiling in acetic acid or potassium hydroxide. 

 The characteristic openings are found in a stained preparation 

 to be covered with a delicate membrane. It is thus made up of 

 three layers, an upper and a lower transparent membrane, in 

 which there are no openings, and a middle layer, which may be 

 colored deeply with magenta, and in which there are open 

 spaces. The two colorless layers correspond with the mern- 



