THE SALIVARY GLANDS. ::':, 



lu Undying t] realisation of one of those lobules, it will bo observed 



that it is made up of iniiuy very small secondary lobules or acini, wliich are 

 ilicins.-lvrs due to tlu! agglomeration of ininutu elementary vesicles or 

 follicles. \\hose average diameter is from l-500th to l-1200th of an inch; 

 these open into the little canal belonging to eacli of the secondary lobules, 

 and which again joins those of the other acini of the primary lobule, to form 

 u single duct. 



The minute elementary vesicles or follicles, the glandular cuh-de-sac (or 

 ultimate follicles) consist of a thin amorphous membrane (membrana propria), 

 lined by a layer of polygonal epithelium cells. (They are closely sur- 

 rounded by a plexus of capillary blood-vessels). 



NN lien tlie salivary lobules remain isolated, this canal, wliich is designated 

 AS excretory, l>ecauso it carries from the lobule the saliva secreted within the 

 elementary follicles, opens directly into the mouth. But when, on the 

 contrary, they all unite and form a single gland, their excretory canals 

 finally converge into one or more principal ducts, whose termination in 

 every case takes place in the same manner by opening into the mouth 

 from the summit of a more or less salient tubercle, an arrangement which 

 1(59. Fig. 170. 



I -MUM HI ..|.\Mi. IN. I, r | I.], WITH CAPILLAHV NKT\\o|;K Alior.NH Till: Inl.l.l- 

 Ml.l:< I l:V. \M- M\'.\|| II. l> ."" KIAMl.i - OF TIIK PAICOT1I) i;i.AM>. 



renders tlie introduction of particl-s of food into tlieso excretory orifices 

 Romewliat difficult. Tlie fibrous and elastic walls of these ducts are lined 

 inten.ally by columnar epithelium. 



It' to tlie fundamental tissue just described, bo added arteries, veins, and 

 lijiii]ilinl!<-H. which convey the materials of secretion and nutrition, as well as 

 tlie iii'i-rt'* which rcgiiliiti! the secretory and nutritive acts, all the elements 

 tut' ring int > the organisation of the salivary glands are made kn<>-.\n. 



The most voluminous of these glands or those \\hich comprise a very 



number of agglomerated lobules, will bo h'rst noticed. They are 



the jui rut ill. niii.iillitri/. Ktihliiiijiial, and iimlnr t/lunilx, which are all pairs, and 



an- placed in proximity to the mouth when they do not lie immediat> ly 



beneath the iidhen^it face of its mucous mcmbnino. Secondly, the less ini- 



iands those which are spread in layers under that membrane, ami 



including the lnlx'nl. lui</inil. and jxifiituK' ijlmul*. will bo examined. 



1. ParotM (,'lnn,l. (Figs. 110; 172.8). 



.nniliim This KllU"li with its cxcr.-ti.ry OtDftl, i- MflO al'ti-r tli' Mii-'al uf tliO 

 cervico-fiK-iii! .-iiln-iii.iiif..us und |iari>ti<l(>-nui-iculaiis im: 



The parotiil gland is situated in the sj.uce included bet\v> en the posterior 



