450 THE SALIVARY GLANDS, BY E. F. W. PFLUGEE. 



breaks up into several filaments, so that groups of branched 

 processes appear to have budded forth from the columnar cells, 

 which often form thick brushes, the base of which is formed by 

 the small columnar cell. In the next place, the free extremity 

 of these fibres is enlarged into a kind of head, resembling a 

 small club, that forms a minute corpuscle (fig. 94). These 

 clavate extremities may be seen to increase in size till they are 

 clearly distinguishable as cell nuclei, surrounded by a sparing 

 quantity of protoplasm. This process of formation of nuclei 

 commences from infinitesimally small points in the fibre, and 

 extends towards the columnar cells, so that two, three, or even 

 very many may originate in one fibre. The small clavate ex- 

 tremities gradually enlarge to form salivary cells, and after a 

 time it is not difficult to find such epithelial cells constituting 

 the mosaic-work of the alveoli, and directly continuous with 

 the columnar cells by means of processes (fig. 94, E). Usually 

 the processes are of such a form that the fibres of the brush 

 attached to the columnar cell increase in size as they recede 

 from it, and develop a very delicate protoplasm, in which larger 

 or smaller nuclei are contained. 



Since it always occurs that a large section of a salivary tube 

 is implicated in this remarkable process of cell formation, 

 and since the most active growth takes place upon the mem- 

 brana propria, the wall will be found to be enormously thick- 

 ened and laminated, with primary and secondary projections, 

 whilst the young cells enlarge and arrange themselves in the 

 form of a mosaic. But coincidently the connective tissue pro- 

 jects inwardly into the thick wall, separating off the cells 

 into alveolar-like groups. I have observed this process 

 of the projection of alveoli en masse, as it were, from the 

 salivary tubes of a columnar cell, particularly well in the sub- 

 lingual gland of the rabbit. The degree of ripeness which the 

 various cells contained in one alveolus exhibit is not always 

 the same ; thus it is customary to meet with a few young cells 

 at the periphery of the alveoli in mucous glands (such as the 

 submaxillary of the dog, ox, and rabbit). How is this process 

 of new formation of salivary cells to be explained ? They are 

 formed in the processes of the columnar cells, without the 

 nucleus being in any way implicated ; for, even when these 



