1 86 ELEMENTS OF HISTOLOGY. [Chap. xxn. 



and filled with coarse granules ; during secretion 

 these granules become used up, so that the cell- 

 substance grows more transparent, beginning from the 

 outer part of the cell and gradually progressing to- 

 wards the lumen of the alveolus. 



248. Blood-vessels and lymphatics. The 

 lobules are richly supplied with blood-vessels. The 

 arteries break up into numerous capillaries, which 

 with their dense networks surround and entwine the 

 alveoli. Between the interalveolar connective tissue 

 carrying the capillary blood-vessels and the inembrana 

 propria of the alveoli exist lymph spaces surrounding 

 the greater part of the circumference of the alveoli 

 and forming an intercommunicating system of spaces. 

 They open into lymphatic vessels accompanying the 

 intralobular ducts, or at the margin of the lobule 

 directly empty themselves into the interlobular 

 lymphatics. The connective tissue between the lobes 

 contains rich plexuses of lymphatics. 



249. The nerve-branches form plexuses in 

 the interlobular tissue. In connection with them are 

 larger or smaller ganglia. They are very numerously 

 met with in the sub-maxillary, but are absent in the 

 parotid. Some ganglia are present in connection with 

 the nerve-branches surrounding the chief duct of the 

 sub-lingual gland. 



Pfliiger maintains that the ultimate nerve-fibres 

 are connected with the salivary cells of the alveoli 

 in man and mammals, but this remains to be proved. 



