LESSON X. 



CONNECTIVE TISSUE. 



1. Elastic Tissue (h. p.). Tease out in salt solu- 

 tion a thin strip of fresh ligamentum nuchae, e.g. of ox. 

 It is almost entirely made up of rather large, branching, 

 and anastomosing fibres having distinct outlines, and 

 curling at their ends. 



Irrigate with acetic acid (1 to 5 p.c.) ; the elastic 

 fibres are unaffected ; the small amount of white 

 fibrous tissue present, swells up ; a few nuclei only 

 come into view. 



2. Network of fine elastic fibres. Stretch a fat-free part of 

 the mesentery of a rat or other mammal 1 , by holding up the 

 intestine, moisten it on both sides with strong alcohol, in a few 

 minutes cut out a piece, place it in 95 p.c. alcohol and brush 

 both sides to remove the surface epithelioid cells. Place it in 

 orcein solution (cp. p. 311) and leave for a day or better for two 

 days, wash with water, look at it with a low power, and if the 

 surface epithelioid cells remain, brush them off, put it in acid 

 alcohol for about a minute, moving it about, then pass through 

 95 p.c. alcohol, clove oil, and mount in balsam. It is best to 



1 The mesentery of a frog will also serve but the blood vessels are 

 a little in the way. 



