30 



THE HUMAN MECHANISM 



If the gland were to be cut in two in any direction with 

 a sharp knife, we should see at once that it is composed of 

 separate parts, or lobes, and that these lobes are still further 

 divided into smaller portions, or lobules. The lobules and 

 lobes are bound together with a rather loose connective tissue 

 which is continuous with a somewhat denser layer surround- 

 ing the gland and forming its capsule ; the connective tissue 



between the lobes forms 

 the primary septa (sing., 

 septum) and that between 

 the lobules the secondary 

 septa. The relation of 

 these structures is shown 

 in Fig. 20. With the aid of 

 the microscope we find that 

 each lobule is still further 

 divided by connective tis- 

 sue into flask-shaped struc- 

 tures, or alveoli (sing., 

 alveolus) : in these the se- 

 cretion, saliva, is manufac- 

 tured and from them it is 

 discharged into the duct of 

 which the alveoli are the 

 blind ends (Fig. 21). 



The whole gland may be 

 compared to a large bunch 

 of grapes ; the main tubular 

 duct of the gland branches (in the septa of connective tissue) 

 very much as the stem of the bunch of grapes branches ; and 

 just as the branches and subbranches of the stem lead, when 

 followed up, to the grapes themselves, so the branches of the 

 duct lead to the alveoli of the gland. If now we pack the 

 bunch of grapes in a small basket of sawdust or cork waste, 

 as Malaga grapes are packed, so that the sawdust fills up 



FIG. 20. Diagram of a cross section of 

 a gland 



Showing its division by primary septa (S) 

 into lobes and by secondary septa (s) into 

 lobules; also the origin of the larger 

 branches of the duct (D) in the lobes and 

 lobules. The beginnings of the duct are 

 shown in Figs. 21 and 22 



