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JOHN SUNDWALL 



diameters of various ducts were ascertained and then compared 

 with the former. Even with this aid it was impossible (and not 

 essential) to classify all ducts. 



Vital staining 



Vital staining with pyronin (Technique VI, 1) greatly facili- 

 tates the study of the smaller ducts and their distribution. Bens- 

 ley found that the entire duct system of the pancreas was stained 



Fig. 6c Lobule of gland, fresh, after vital staining with pj-ronin. Drawing, 

 binocular. The lumina of ducts are deeply stained red. A, intralobular duct; 

 B, interlobular duct. 



by this method. In application of his methods to the lachrymal 

 gland it was found that its duct system stains a deep red while 

 the tubules are only faintly stained (fig. 6 c). In the larger ducts 

 the stain is limited to the periphery of the lumen, while in the 

 smaller ducts the entire lumen stains. The smaller intralobular 

 and intercalary ducts are especially prominent, and when fresh 

 sections 0.5 mm. thick are examined through the binocular 

 microscope the ramifications are clearly seen. The deep red 

 ducts can be readilv traced, in thin sections, to the acini. Verv 



