82 PRACTICAL HISTOLOGY. 



Preparation 9. Elastic Network. The pro- 

 portion of elastic fibres varies considerably according 

 to the part from which the connective tissue under 

 examination is taken. Some serous membranes con- 

 tain a large number of elastic fibres; and since they 

 are readily spread out in their natural condition the 

 network which these fibres form by their branchings 

 and conjunctions is easily made evident. One of 

 the best objects for this purpose is to be found in the 

 rabbit's mesocolon. A piece of this, moistened with 

 a little salt solution, may be spread out as flat as 

 possible upon a slide, and a drop of dilute acetic acid 

 (one per cent.) having been placed on a cover-glass, 

 this is inverted over the tissue. The white fibrils 

 quickly swell up and become indistinct, whilst the 

 elastic network comes clearly into view. The pre- 

 paration may be made permanent by putting, as in 

 former preparations, a drop of glycerine at the edge 

 of the cover-glass, and after this has had time to dif- 

 fuse itself, cementing the edges with chloroform bal- 

 sam as usual. 



Preparation 10. Elastic Tissue. The elastic 

 ligaments are to be regarded merely as connective 

 tissue structures in which the elastic elements of the 

 tissue preponderate. There is always a quantity of 

 ordinary areolar tissue amongst the elastic fibres 

 even here, but not sufficient to obscure them, espe- 

 cially as they are generally of larger size as well as 

 in greater number than elsewhere. It is sufficient, 

 in order to see them, simply to teaze out a portion of 

 the ligamenta subflava of the vertebrae or other 

 elastic tissue in water or salt solution. If it be 

 desired to keep the preparation it can be mounted 

 in glycerine. 



Preparation 11. Section of Elastic Fibres. 

 To observe the shape of the fibres a transverse section 

 may be made of a piece of ligamentum nuchae of the 

 ox, in which the fibres are extremely large. 



In order to obtain the requisite firmness for cut- 

 ting, place a small piece of the ligament in a quantity 



