184 ELEMENTARY PHYSIOLOGY. [XVII. 



spirit ; place others in osmic acid 1 p.c. for half 

 an hour, wash and place in 75 p.c. alcohol. 

 In sections of these pieces note that there are no 

 villi and no proper glands of Lieberkiihn. The 

 mucous membrane is however thrown up into 

 considerable folds. In the osmic acid specimens, 

 the cells will probably be so full of deeply 

 stained fat globules that little structure can be 

 seen in them except the hyaline free border ; in 

 the sub-mucous connective tissue few or no fat 

 globules are seen. 



In the alcohol specimens the cell substance will 

 be seen as a distinct sponge-work or network, 

 the fat globules having been dissolved. 



B. Bile. 



1,. Test the reaction of bile' with litmus paper. If 

 fresh it is slightly alkaline or neutral, 



2. To a small quantity add strong acetic acid drop by 

 drop. A curdy precipitate of mucin coloured with 

 the bile-pigment will be thrown down. Since the 

 mucin of bile is not formed in the liver but in the 

 mucous glands and cells of the gall-bladder and 

 duct, the lohger the bile has been in the gall- 

 bladder the greater the precipitate which will 

 be obtained. 



For the following tests (§§ 4, 5) it is best, although 

 not necessary, to precipitate the mucin with acetic 



' Ox-gall or sheep's gall may be obtained from a butcher's. 



