LESSON X. 



THE CONNECTIVE TISSUES (continued). 



ELASTIC TISSUE, FIBROUS TISSUE, SPECIAL VARIETIES, DEVELOPMENT 



OF CONNECTIVE TISSUE. 



1. TEASE out as finely as possible a small shred of elastic tissue (ligarnentum 

 nuchae of the ox or liganienta subflava of man) in Farrant's solution l and 

 cover the preparation. Note the large well-defined fibres constantly branching 

 and uniting with one another. Look for transverse markings on the fibres. 

 Measure three or four. Sketch a small part of the network. Note the 

 existence of bundles of white fibres amongst the elastic fibres. 



2. Mount in Farrant a thin transverse section of ligamentuni nuchae 

 which has been hardened in 2 per cent, solution of bichromate of potash. 

 Observe the grouping of the fibres and their angular shape. Sketch one or 

 two groups. 



3. Pinch off the end of the tail of a dead mouse or rat, draw out the long 

 silk-like tendons and put them into saline solution. Take two of the longest 

 threads and stretch them along a slide, letting the ends dry firmly to the slide 

 but keeping the middle part moist. Put a piece of hair between them and 

 cover in saline solution. Observe with a high power the fine wavy fibrillation 

 of the tendon. Draw. Now run dilute acetic acid under the cover-glass, 

 watch the tendons where they are becoming swollen by the acetic acid. 

 Notice the oblong nucleated cells coming into view between the tendon 

 bundles. Sketch three or four cells in a row. Lastly, lift the cover-glass, 

 wash away the acid with distilled water, place a drop of hseinatoxylin solution 

 on the tendons, and leave the preparation for fifteen minutes or more ; then 

 wash away the logwood and mount the preparation in acidulated glycerine. 

 Cement the cover-glass with gold size. 



4. Immerse one or two other pieces of tendon in nitrate of silver solution 

 (1 per cent.) for ten minutes, then wash them in distilled water, stretch 

 them upon a slide, mount in Farrant, and expose to the sunlight. 



5. Stain with magenta solution * a thin section of a tendon which has 

 been hardened in alcohol. Mount in dilute glycerine and cement the cover- 

 glass at once. Sketch a portion of the section under a low power. 



Elastic tissue is a variety of connective tissue in which the elastic 

 fibres preponderate. It is found most characteristically in the liga- 

 mentum nuchte of quadrupeds and the ligamenta subflava of the 

 vertebras, but the connective tissue of other parts may also have a con- 



See Appendix. 



D 2 



