180 JOHN SUNDWALL 



they are smaller and more cuboidal and the secreting end has a 

 tubular form. This doubtless explains in a large measure the 

 controversy regarding the structure of the secreting terminals — 

 whether tubules or acini. The finer structure of the cells of 

 tubules is considered in the Section on granules. 



V. SECRETION GRANULES 

 Serous cells^ 



For some time there was much discussion as to whether the 

 granules seen in fixed preparations of glands were natural or the 

 product of fixation. A. Fischer ('99) regarded them as artefacts — 

 Fallungsprodukte. E. Miiller, ('96) on the other hand, found 

 that certain granules seen in fresh cells became more distinct 

 when fixed with sublimate solution. The process of fixation 

 was directly observed through the microscope. Held ('99) 

 and many others have substantiated Miiller's observations, and 

 now secretion granules are no longer regarded as artefacts. 

 Milawsky and Smirnow ('93) studied, in the parotid and sub- 

 maxillary glands of dogs, the secretory changes resulting from 

 electrical stimulation of the cerebral and sympathetic nerves 

 supplying these glands. 



Bensley ('96) among others (see his various papers for bibliog- 

 raphy) has contributed much to our knowlege of the anteced- 

 ent substance which goes to make up the granules of serous 

 cells. He has observed that 



During digestion a substance similar in chemical properties to the 

 chromatin of the nucleus makes its appearance in the outer clear zone 

 of the chief cells of the fundus glands. This substance, which may be 

 called prozymogen, stains deeply and readily in haematoxylin, and 

 presents a characteristic fibrillated appearance. (He suggests that in 

 some cells this is dissolved in the nuclear substance and that sometimes 

 it is collected in masses — plasmosomata.) During rest this proxy mogen 

 is used in some way giving rise to zymogen granules. 



Speaking of the chief cells he states that the fibrillae in the 

 outer zones of the cells are not so regular or distinct as in the 



* Metzner ('07) in Nagel's Handbuch der Physiologie des Menschen gives an 

 excellent discussion of secretion granules in general. 



