THE LACHRYMAL GLAND 165 



duct system — interlobular and intralobular ducts- is similar. 

 The intercalary ducts, on the other hand, as a rule branch off at 

 almost right angles or even greater angles from the intralobular 

 ducts from which they have origin (fig. 6 b). Of course there 

 are numerous exceptions to this generalization, but it is not 

 by any means imaginative to compare these corrosion casts of 

 the lachrymal gland to six or eight trees varying in length and 

 placed in a line so closely that the smaller branches and leaves 

 intermingle. The main trunks are then comparable to the 

 Ductuli excretorii; and the primary, secondary, and tertiary, etc. 

 branches to the primary, interlobular, and intralobular ducts. 

 The lea^'es represent the acini or tubules and their stems the 

 intei'calarv ducts. 



r^ 



" B 



Fig. 6b Corrosion cast. High power drawing, projection apparatus. A, 

 intralobular duct; B, intercalary duct; C, tubule. 



In preparations where the mass has not passed beyond the 

 nodular enlargements of the intralobular ducts the branching 

 is readily observed through the binocular microscope. If the 

 mass has passed into the tubules the duct system is greatly 

 obscured. For the study of the intercalary ducts and tubules, 

 small pieces were teased off and mounted on slides, then studied 

 by high power. 



It must be appreciated that in the study of corrosion casts, it 

 is impossible to classify with certainty the various ducts; i.e., one 

 cannot differentiate between the larger intralobular and the 

 smaller interlobular ducts. As an auxiliary to this study carmin 

 gelatin was injected into the ducts of other glands and sections 

 of these tissues were prepared. In the latter preparations the 



