Joseph Marshall Flint 277 



during the digestion, rendered the corrosions unreliable as a means 

 of determining accurately the caliber of the ducts. These data are 

 naturally best obtained by direct measurements of the distended duct 

 in fresh subjects. In a general way, however, the relations in size are 

 well preserved, although one would hesitate to apply methods of accur- 

 ate mensuration to them. Of course the ducts in all parts of the gland 

 are under the same general conditions so that the effect of shrinkage in 

 one part would be about commensurate with that in another. And 

 even while we can assume that this method gives a general idea of the 

 relative size of these structures, under no circumstances, however, would 

 we be justified in drawing conclusions from material of this nature as 

 to their exact caliber in life. 



In general the method of branching appears to be dichotomous, 

 although often unequally so. The diameter of the two branches after 

 a division is usually unequal, a fact which is especially true of the 

 larger divisions. The rule of dichotomy holds nevertheless through- 

 out the entire secretory system, both intra- and extralobular, with the 

 single exception of the intercalary ducts where three or even four ducts 

 are often given off at a single node. The ultimate alveolar ampullge, 

 likewise, violate this law since three, four, or five of them always termi- 

 nate the secretory system (Fig. 3). 



The commonest distribution of the ducts is represented in Fig. 1, 

 where the primary branches or ducts of the first order spread out 

 irregularly from a short and twisted trunk radiating in various direc- 

 tions from the hilus. Since the Glandula submaxillaris is about three 

 times as long as it is thick, the branching must be less in the plane of 

 lesser than in the one of greater dimension. Except at the hilus the 

 ducts run, in general, as far away from the capsule as the anatomical 

 conditions which require the drainage of the entire organ will permit. 

 In the human gland the primary ducts do not pass alternately to one 

 and then the other side of the organ, as they do in embryo pigs, but 

 arise rather irregularly from the main trunk. They correspond, how- 

 ever, to the primary divisions of the ducts in embryo pigs and if they 

 had preserved the same regularity of distribution observed in the 

 embryo they might perhaps be justly called lobar ducts. Owing, how- 

 ever, to the mechanics of development which crowd the gland into the 

 small angle between the mandible and adjacent muscles the organ be- 

 comes distorted and its different portions have unequal opportunities for 

 growth. Apparently these primary ducts have the same general cali- 

 ber, although it is not uncommon to observe considerable variations in 

 their diameter indicating that they drain unequal volumes of glandular 

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