THE CONNECTIVE TISSUES. 45 



LESSON X. 



THE CONNECTIVE TISSUES (continued^. 



ELASTIC TISSUE, FIBROUS TISSUE, DEVELOPMENT OF CONNECTIVE TISSUE. 



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

 nuchse of the ox or ligamenta subflava of man) in glycerine and water, 

 slightly coloured by magenta. Cover and cement 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. Examine a thin transverse section of ligamentum nuchae which has been 

 hardened in 2 per cent, solution of bichromate of potash. The section is to 

 be stained with hsematoxyliii and mounted in Canada balsam by the usual 

 process, 1 or simply in glycerine and water. Observe the grouping of the 

 fibres and their angular shape. Notice also the nuclei of connective-tissue 

 cells amongst the fibres. 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 (0'75 per cent.) 

 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 

 Delafield's hgematoxylin solution on the tendons, and leave the preparation 

 until it is deeply stained ; then wash away the logwood and mount the pre- 

 paration in acidulated glycerine. Cement the cover-glass with gold size. 



4. Take one or two other pieces of tendon, and, after washing them in 

 distilled water, stretch them upon a slide as before, fixing the ends by 

 allowing them to dry on to the slide. Put a drop of nitrate of silver solution 

 (1 per cent.) 011 the middle of the tendons, and leave it on for five to ten minutes, 

 keeping the preparation in the dark. Then wash off the silver nitrate with 

 distilled water, and expose the slide to direct sunlight. In a very few 

 minutes the silvered part of the tendons will be brown. As soon as this is 

 the case, dehydrate the tendons with alcohol in situ upon the slide, run off 

 the alcohol, and at once put a drop of clove-oil on the preparation. In a 

 minute or two the clove-oil can be replaced by Canada balsam in xylol, arid 

 covered. 



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

 hardened in 70 per cent, alcohol. Mount in dilute glycerine and cement the 

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



1 See Appendix. 



