THE MIXED SALIVA IN THE MOUTH. 21 7 



[Water, 



Solids, 



Soluble organic bodies (ptyalin), 

 Epithelium, mucin, , 

 Inorganic salts, 



Potassic sulphocyanide, . . 

 Potassic and sodic chlorides, 



Gases. Pfluger found that 100 cubic centimetres of the saliva contained 0*6 ; 64 '7 C0 2 

 (part could be pumped out, and part required the addition of phosphoric acid) ; 0'8N. ; or, in 

 100 vol. gas, - 91 O ; 97*88 C0 2 ; 1*21 N. [It therefore contains much more C0 2 than venous 

 blood. Kiilz obtained from 100 c.c. of human saliva 7 c.c. of gas = 1 c.c. , ]S" = 2'5 c.c. and 

 C0 2 = 3'5 c.c. Besides this there is 40-60 c.c. of fixed C0 2 in the form of carbonates.] 



(c) Sub-lingual saliva is obtained by placing a very fine cannula in the 

 ductus Rivinianus; it is strongly alkaline in reaction, very sticky and cohesive, 

 contains much mucin, numerous salivary corpuscles, and some potassium sulpho- 

 cyanide. 



147. THE MIXED SALIVA IN THE MOUTH. The mixed saliva in the 



mouth is a mixture of the secretions from the salivary, mucous, and other glands of 

 the mouth. 



(1) Physical Characters. It is an opalescent, tasteless, odourless, slightly 

 glairy fluid, with a specific gravity of 1004 to 1009, and an alkaline reaction. The 

 amount secreted in twenty-four hours = 200 to 1500 grammes (7 to 50 oz.); 

 according to Bidder and Schmidt, however, = 1000 to 2000 grammes. The solid 

 constituents = 5-8 per 1000. 



Composition. The solids are : Epithelium and mucus, 2*2 ; ptyalin and albumin, 1*4 ; salts, 

 2 - 2; potassium sulphocyanide, 0*04 per 1000. The ash contains chiefly potash, phosphoric 

 acid, and chlorine {Hammerhacher). 



Decomposition-products of epithelium, salivary corpuscles, or the remains of food, may render 

 it acid temporarily, as after long fasting, and after much speaking ; the reaction is acid in some 

 cases of dyspepsia and in fever, owing to the stagnation and insufficient secretion. 



(2) Microscopic Constituents. (a) The salivary corpuscles are slightly larger 

 than the white blood-corpuscles (8 to 11 /x), and are nucleated protoplasmic globular 

 cells without an envelope (fig. 150, s). During their living condition, the particles 

 in their interior exhibit molecular or Brownian movement. The dark granules 

 lying in the protoplasm are thrown into a trembling movement, from the motion of 

 the fluid in which they are suspended. This dancing motion stops when the cell 

 dies. 



[The Brownian movements of these suspended granules are purely physical, and are exhibited 

 by all fine microscopic particles suspended in a limpid fluid, e.g., gamboge rubbed up in water, 

 particles of carmine, charcoal, &c] 



(&) Pavement epithelial cells from the mucous membrane of the mouth and tongue ; they 

 are very abundant in catarrh of the mouth (fig. 150). 



(c) Living organisms, which live and thrive in the cavities of teeth, nourished by the remains 

 of food. Amongst these are Leptothrix buccalis (fig. 149, 12) and small bacteria-like organisms. 

 The threads of the leptothrix penetrate into the canals of the dentine, and produce dental caries. 

 {Miller has found twenty-five varieties of micro-organisms, including cocci, bacteria, vibrios, 

 spirilla, and spirochsetse, eight of them present in the stomach and twelve in the intestines.] 



(3) Chemical Properties. (a) Organic Constituents. Serum-albumin is preci- 

 pitated by heat and by the addition of alcohol. In saliva, mixed with much water 

 and shaken up with C0 2 , a globulin-like body is precipitated ; mucin occurs in small 

 amount. Amongst the extractives, the most important is ptyalin ; fats and urea 

 occur only in traces. In twenty-four hours 130 milligrammes of potassium or 

 sodium sulphocyanide are secreted. 



(b) Inorganic Constituents. Sodium and potassium chlorides, potassium 

 sulphate, alkaline and earthy phosphates, ferric phosphate. 



