20 PRACTICAL HISTOLOGY. 



CONNECTIVE TISSUE. 



CONNECTIVE TISSUE occurs in a variety of forms, as areolar tissue, or membranes, or forming 

 fascia; and tendons. In whatever form it occurs we have to study two classes of structural ele- 

 ments, viz. fibres and corpuscles. The fibres are of two kinds, (a) the white or gelatigenous, so 

 called because they yield gelatine on boiling ; (b) the yellow or elastic, which yield elastin. The 

 corpuscles are of three kinds : (a) the fixed connective-tissue corpuscles, which always bear a 

 definite relation to the white fibres ; (6) amoeboid or wandering cells, which are identical with 

 colourless blood-corpuscles or leucocytes. They wander freely in the lymph-spaces by virtue 

 of their contractility ; (c] the so-called plasma cells, of which the exact relation is not made out. 



ELASTIC TISSUE. 



A. IN THE FRESH STATE. 



PREPARATION. Tear off, in the axis of the fibres, with a forceps, a very fine piece of the 

 fresh ligamentum nuchae of an ox. Tease it out in a drop of salt solution or water, with 

 two needles, and cover. It is convenient to use a low power to ascertain when the piece is 

 sufficiently teased. 



EXAMINATION (H). Notice the homogeneous transparent fibres, about the breadth of a 

 human coloured blood-corpuscle. They have a yellowish tinge, and their margins are well- 

 defined. They branch and anastomose and may curl up at the ends (PL IV., Fig. i). 



EFFECT OF REAGENTS. Irrigate the preparation with a one per cent, dilution of acetic 

 acid. The fibres are not affected thereby. To preserve this preparation substitute Farrant's 

 solution for the acid watery fluid. 



B. PERMANENT PREPARATIONS. 



Excellent permanent preparations are obtained by the following method. Place small 

 pieces about half-inch cubes in many times their bulk of chromic and nitric acid fluid 

 (p. xxxiii) for a week. After that soak the pieces in water for twenty-four hours, to remove all 

 traces of the acid, and preserve them for use in methylated spirit. Make longitudinal and 

 transverse sections in the usual way. 



Stain a longitudinal and a transverse section in picrocarmine for ten minutes. 



EXAMINATION (H) of the longitudinal section reveals the elastic fibres stained of a deep 

 yellow, with their characteristic branches and anastomoses. Between them a small amount 

 of ordinary connective tissue stained red is seen. 



The transverse section shows the cut ends of the fibres, as solid yellow polygonal bodies in 



