Joseph Marshall Flint 283 



group of vessels are fine fasciculated bands of connectiA'e tissue which 

 form the interlobular spaces. These can be made out in digested speci- 

 mens both by the position of the vessels and the darker areas which 

 they produce as they pass between the lobules. Fig. -i is a repre- 

 sentation of the submaxillary of a dog prepared by this method. The 

 ducts and vessels lie in a sublobular interspace embraced by the con- 

 nective tissue which is seen in cross-section at the edge of the block of 

 tissue. The larger duct in this space runs for only a short distance 

 before entering the lobules and is, therefore, of the order of sublobular 

 ducts. The lobular ducts which are given off from this branch pass 

 through the hilus of the lobules carrying with them considerable con- 

 nective tissue derived from the interspace from which they come (Figs. 

 4 and 5). After penetrating the lobule they run to the center of that 

 structure and then begin to radiate towards its periphery. The intra- 

 lobular ducts can be distinguished from the blood-vessels by their cali- 

 ber and the delicacy of the walls. Isolated terminal branches are seen 

 towards the perijDhery of the lobule, but in no instance does a duct ever 

 seem to reach the limiting membrane, a layer of one or two alveoli 

 always intervening. The frame-work within the lobule and its rela- 

 tion to the ducts is exquisitely shown in these preparations; the strands 

 of connective tissue entering at the hilus, the fine delicate limiting mem- 

 brane embracing it, and the basement membranes of the alveoli are all 

 patent, the latter appearing like a delicate web throughout the whole 

 lobule. This is firmly attached to the limiting membrane on the one 

 hand Avhere it forms a sort of mosaic, and to the Avails of the ducts and 

 vessels on the other, so that the support of these structures is given by 

 the alveolar frame-Avork, and they are, as it Avere, swung in the mesh- 

 Avork of delicate reticalnted basement membranes. 



In ordinary sections, the Ductus submaxillaris is lined by a double 

 layer of epithelial cells, the inner of AA'hich is irregularly columnar and 

 has oval nuclei which stain deeply and shoAV distinct gatherings of chro- 

 matin substance upon the linin filaments. These cells interdigitate with 

 those of the outer layer which are more conical and polyhedral in shape, 

 and are, as a rule, considerably smaller. The nuclei of the latter are 

 smaller, somewhat more deeply stained and often more vesicular in 

 shape. The tAvo layers of epithelial cells rest upon the basement mem- 

 brane of the duct which is immediately embraced by the fasciculated 

 intertAAdning strands of AA'hite fibrous tissue and reticuhmi. Immediately 

 external to the epithelial layer of basement membrane is a dense mesh- 

 work of elastic fibres which interlace Avith the fibres of reticulum and 

 white fibrous tissue. The few smooth muscle fibres described by von 



