X] CONNECTIVE TISSUE 71 



examine it before putting in clove oil, in order to see that the 

 white fibrous tissue is sufficiently decolourized ; if left too long 

 in alcohol the elastic tissue also will be decolourized. Observe 

 (h.p.) the close network of stained elastic fibres. 



3. Tendon. Cut off the tip of the tail of a 

 recently killed young rat; cut away the skin for a 

 short distance, break off a vertebra, and pull straight 

 outwards. A bundle of small tendons will be obtained. 

 (A similar bundle can be obtained in the same way 

 from each vertebra.) Gently stretch this over a glass 

 slide from edge to edge, and hold it in this position till 

 the edges are dry, touching the mid portion with a 

 brush moistened with normal saline solution ; the fibres 

 are thus kept extended. Cover with a cover-slip. 

 Note the white fibres consisting of parallel bundles 

 of wavy fibrils. Slowly irrigate with acetic acid 1 p.c., 

 watching the while under a high power. Between the 

 bundles of fibrils rows of cells will become visible. 

 Note in each the round or oval nucleus, the rectangular 

 outline of the cell, and the finely granular cell substance. 

 Indications of flange-like lateral processes may be seen 

 as lines running along the cells in the direction of the 

 tendon. After the acetic acid has been added for some 

 little time the cell substance becomes very indistinct, 

 and between the swollen bundles scarcely anything is 

 seen but rows of elongated shrunken nuclei. (Cp. 

 action of acetic acid on cartilage cells, Lesson IX. 1 b.) 



4. fibrils of tendon. Place a piece of tendon (see 3) in a 

 saturated aqueous solution of picric acid for a day. Wash with 

 water, renewing it as it becomes coloured, for about a quarter of 

 an hour. Place it in a watch-glass with a 75 p.c. alcoholic 

 solution of acid magenta of such strength that the tendon is easily 



