210 UNORGANISED FLUIDS. 



by means of the microscope, which reveals the presence of 

 mucous epithelial scales in all stages of their development ; 

 as the scales found in the sweat are derived from the desqua- 

 mation of the epidermis, so are those of the saliva and mucus 

 from that of the epithelium. 



The saliva as well as the sweat yields on evaporation 

 crystals of the various salts referred to in the analysis. 



Blood corpuscles are sometimes present in the saliva and 

 mucus ; these proceed usually from the gums. 



The uses of the saliva in the animal economy are classified 

 by Dr. Wright as follow : 



Active. 1. To stimulate the stomach and excite it to ac- 

 tivity by contact. 2. To aid the digestion of food by a 

 specific action upon the food itself. 3. To neutralise any 

 undue acidity of the stomach by supplying a proportionate 

 alkali. 



Passive. 1. To assist the sense of taste. 2. To favour 

 the expression of the voice. 3. To clear the mucous mem- 

 brane of the mouth, and to moderate thirst. 



THE BILE. 



The bile, like the unorganised fluid already described, pre- 

 sents but little of interest to the microscopist in its normal 

 state. 



It happens, however, occasionally, when it has been re- 

 tained in the gall-bladder for a long time, in consequence of 

 which it has become inspissated, that it does contain solid 

 and coloured particles. 



These particles have been noticed by Scherer* and also by 

 Dr. H. Letheby of the London Hospital, who was so con- 

 siderate as to transmit, for my examination, a portion of in- 

 spissated bile, containing them, as also plates of cholesterine, 

 in great numbers. 



The bodies in question consist of two parts, an external 

 colourless investing portion, and an internal coloured and 

 granular matter ; this disposition of the colouring matter im- 



* Untersuchungen, &c., p. 103. 



