THE MIXED SALIVA IN THE MOUTH. 293 



may render it acid temporarily, as after long fasting, and after much speaking 

 (Hoppe-Seyler). Even outside the body, saliva containing much epithelium 

 becomes acid before it putrifies (Gorup-Besanez). 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 (8-11 /x), and are nucleated pro- 

 toplasmic globular cells without an envelope. 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.] 



(6.) Pavement epithelial cells from the mucous membrane of the mouth and 

 tongue ; they are very abundant in catarrh of the mouth (Fig. 115, 8). 



(e.) Living organisms, which live and thrive in the cavities of teeth nourished 

 by the remains of food. Amongst these are Leptothrix buccalis (Fig. 115, 12) 

 and small bacteria-like organisms. 



(3.) Chemical Properties (a.) Organic Constituents. Serum-c 

 is precipitated 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 (Berzelius) ; 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, potas- 

 sium sulphate, alkaline and earthy phosphates, ferric phosphate. 



Abnormal Constituents. In diabetes mellitus, lactic acid, derived from a 

 further decomposition of grape-sugar, is found (Lehmann). It dissolves the 

 lime in the teeth, giving rise to diabetic dental caries. Frerichs found leucin, and 

 Vulpian increase of albumin in albuminuria. Of foreign substances taken into 

 the body, the following appear in the saliva : Mercury, potassium, iodine, and 

 bromine. 



Saliva of New-born Children. In new-born children, the parotid 

 alone contains ptyalin. The diastatic ferment seems to be developed 

 in the sub-maxillary gland, and pancreas at the earliest after two 

 months. Hence, it is not advisable to give starchy food to infants. 

 No ptyalin has been found in the saliva of infants suffering from 

 thrush (Oidium albicans Zweifel). 



The diastatic action of saliva is not absolutely necessary for the 

 suckling, feeding as it does upon milk. The mouth during the first 

 two months is not moist, but at a later period saliva is copiously 

 secreted (Korowin); after the first six months, the salivary glands 



