THE SALIVARY GLANDS 



97 



also assists in forming the food into a soft mass previous to swal- 

 lowing. 



The rate of the secretion of the saliva is from one to two 

 pounds daily. The secretion is probably continuous, but is always 

 increased by the introduction of a substance into the mouth. This 

 substance need not necessarily be digestible or even tasty, for the 

 saliva may be readily produced by the sucking of a glass bead or 

 a pebble ; and even the odour of a savoury dish will ' make the 

 mouth water.' 



The salivary glands of children do not act till about the fourth 

 or the sixth month. It would seem, therefore, that children should 

 not be fed with foods containing much starch before that age. We 

 shall, however, learn that the saliva is not the only fluid which is 

 capable of digesting starch. 



GLANDS 

 (Function) 



6LANDS 



(Forms) 



SALIVAEY 

 GLANDS 



SALIVA . 



Secreting . . 

 Excreting 



Ductless . . 



Simple . . 

 Compound 



Parotid . . 

 Submaxillary 

 Sublingual . 



r Composition . - 



Uses 



Bate of 

 ^ Secretion 



SUMMARY. 



j Prepare and separate a fluid frcni the blood. 



1 Example salivary glands. 



< Separate waste materials from blood. 



I Example sweat glands. 



, Have no duct. Example the spleen. 



\ Probably engaged in the elaboration of the 



( blood. 



j Tubular. 



\ Lobulated. 



i Tubular. 



\ Lolmlatcd. 



Situated under and in front of the ear. 



Largest. 



Duct opens opposite the second molar. 



Under the lower jaw. 



Size of a large plum. 



Duct opens at the bridle of the tongue. 



Under the tongue. 



Size of an almond. 



Several ducts. 



Water. 



Salts. 



Ptyalin the active principle. 



Other matters. 



Chemical changes starch into grape-sugar. 

 .Moistens mouth facilitates 

 I speaking. 



. , Dissolves savoury substances 

 Mechanical \ _ thus aiding t ' aste 



Assists in swallowing by 

 * forming a soft bolus. 

 From one to two pounds daily. 

 Probably continuous. 

 Accelerated on taking food. 

 None in children till four or six months. 



H 



