CONNECTIVE TISSUE. 23 



EXAMINATION (H). The corpuscles are now clearly brought into view ; their nuclei are 

 stained and their wing-shaped expansions are distinct, in fact, they appear as flat, nucleated 

 plates, sometimes with divided expansions. Elastic fibres are yellow, and white fibres are 

 slightly reddish. 



Annular Constrictions on the White Fibres. Take a small piece of the delicate pia mater 

 lying within the circle of Willis from the brain of a sheep just killed, or slit up the dura 

 mater of the spinal cord of an ox, and remove some of the fine fibres that stretch across the 

 sub-arachnoid space. Spread out the tissue on a slide, and irrigate it with a one per cent, 

 dilution of acetic acid. The fibres swell up, but here and there they exhibit numerous annular 

 constrictions. These constrictions are the indications of the existence of a sheath on the 

 fibres, which is not affected by acetic acid. In some cases a fibre may be found to wind in a 

 spiral manner round the white fibre. These preparations may be stained with picrocarmine 

 or magenta, but they do not keep well. 



The fibres of white fibrous tissue are made up of fibrils, held together by a cement. The 

 fibrils (y-g^y-o inch in diameter) are sometimes revealed by teasing, but it is better to use some 

 chemical reagent to dissolve the cement. 



PREPARATION. Place a narrow strip of the tendo Achillis or other tendon of a rabbit 

 or other animal in a saturated solution of picric acid (p. xxxii) for twenty-four hours After 

 that time wash away the surplus colouring matter, tear off a small shred, and tease it in water. 

 Cover. 



EXAMINATION. The wavy, excessively delicate, non-branched, yellow-coloured fibrils 

 (due to picric acid) are now apparent Each white fibre is made up of a great number of 

 these fibrils, held together by a cement. Usually no cells are seen, but irrigation with a one 

 per cent, dilution of acetic acid readily brings the long oval nuclei of the tendon-cells into view. 



OTHER METHODS. Maceration of a piece of tendon in a saturated watery solution of 

 baryta for four or five hours, and subsequent steeping in water for twenty-four hours or 

 maceration in a large quantity of a ten per cent, solution of common salt for ten days, 

 effect a similar result, but the picric acid method is the most satisfactory and convenient. 



TENDON. 



It is advisable to use a tendon from a young animal, for in such there is a much larger 

 number of corpuscles than in the tendon of an adult. 



PREPARATION. Place pieces of the tendo Achillis of a calf about an inch long and a 

 quarter of an inch thick in many times their bulk of Miiller's fluid (p. xxxii) for fourteen days. 

 Then remove them, and after soaking them in water to remove the chromium salts, preserve 

 them in rectified spirit till sections require to be made in the usual way by freezing. Make 

 both transverse and longitudinal sections. 



TRANSVERSE SECTION. 



(i) Place a section on a slide and cover it with a large drop of logwood solution ; 

 within a few minutes it will be sufficiently stained. Wash away all the surplus logwood and 

 mount the section in Farrant's solution. 



