CONNECTIVE TISSUE. 21 



groups of twos and threes ; when two fibres adhere their opposed surfaces are moulded to 

 each other (PI. IV., Fig. 2). Surrounding each group of fibres is a very small quantity of 

 connective tissue stained red. Only a very small quantity of white fibrous tissue exists in 

 the ligamentum nucha;. If desired similar sections may be tinged with a solution of magenta 

 (p. xliv), which stains the elastic fibres bright red, and is thus a good reagent for detecting 

 their presence. 



Elastic tissue also forms part of ordinary areolar tissue. It occurs in the form of a net- 

 work of fine elastic fibres in the skin, where it will be examined, but its characters may be 

 well studied in the mesocolon of a rabbit. 



PREPARATION. Remove the mesocolon from a newly killed rabbit. Pin it to a piece 

 of flat cork to keep it stretched, and place it, cork uppermost, for three days in a mixture of 

 chromic and nitric acid (p. xxxiii). After washing away all surplus acid, preserve it in methy- 

 lated spirit. Snip off a small piece, float it in water to remove the spirit, and stain it for ten 

 minutes with picrocarmine ; mount it in Farrant's solution. 



EXAMINATION (H). Observe the network of fine elastic fibres one-sixth the breadth of 

 a coloured blood-corpuscle. The fibres are imbedded in white fibrous tissue, which is stained 

 red. 



If desired another piece may be stained with solution of magenta (p. xliv) which stains the 

 elastic network red. Elastic tissue will be further considered with arteries, and in the skin, 

 where the method of preparing it by artificial digestion is described (Stirling) (p. 92). 



f>> 



WHITE FIBROUS TISSUE. 



IN THE FRESH STATE. 



PREPARATION. -Kill a rabbit or a rat, and with scissors snip off a small piece of the 

 delicate connective tissue that lies under the skin, and which connects it to the fasciae. The 

 piece of tissue at once rolls into the form of a ball ; but by placing it on a dry slide it can 

 easily be spread out with needles into a fine membrane, its original form when in situ. 

 During the process do not allow the tissue to dry, which may be prevented by breathing on it 

 from time to time. Add a drop of normal salt solution ; cover and examine. 



EXAMINATION (H). Observe the wavy fibres of white fibrous tissue running in every 

 direction. Their outlines are indistinct, but here and there a longitudinal striation in their 

 course is observable, indicating that each fibre is composed of fibrils. In addition to these, a 

 few fibres which refract the light more strongly may be detected ; these are elastic fibres ; but 

 little else is observable in this preparation, especially if taken from an adult animal (PL IV., 

 Fig. 3)- 



EFFECT OF REAGENTS, (a) Magenta Solution. Irrigate the preparation with solution 

 of magenta (p. xliv), and the existence of the corpuscular element will be revealed. The nuclei 

 of the connective-tissue corpuscles are stained of a red colour by the dye. There are two kinds 

 of corpuscles, one larger than the other. The larger, when seen on the flat, are like large 

 nucleated squames, though they are sometimes branched, and when seen on edge they are 

 fusiform. These are the ' fixed ' connective-tissue corpuscles, and the smaller ones, about the 

 size of the colourless blood-corpuscles, with two or three small nuclei, are the wandering cells, 

 or leucocytes, and are identical with lymph- or colourless blood-corpuscles. The elastic fibres 



