1 6 THE ANATOMY OF THE ADULT HUMAN SALIVARY GLANDS 



develops occasionally on one or both sides in individual cases. When 

 present, the gland is usually small, confined to the cephalic portion 

 of the alveoUngual field, intermediate in position between the mass of 

 the lesser sublingual glands laterally and the mam submaxillary duct 

 mesally. 



Figure lo shows the type in which the duct of the greater sublingual 

 gland joins the submaxillary duct and opens in common with the same 

 by a single orifice on the parafrenular papilla. 



Figure 15 shows an instance in which the greater sublingual gland 

 is present on the left side in an adult human subject, the duct emptying 

 by a separate and independent orifice caudolateral to the submaxillary 

 duct. On the opposite side of the same subject (Fig. 16) the greater 

 sublingual has not developed. I have received the distinct impression 

 that the presence of a greater sublingual or Barthoiinian gland, with 

 separate duct, either opening independently, or joining the terminal 

 of the main submaxillary duct, involves a reduction in the size and 

 extent of the group of lesser sublingual glands. On the other hand the 

 human adults which do not possess a greater sublingual gland show 

 a more extensive development of the lesser sublingual group. 



I have also encountered instances in which the injection of a very 

 minute orifice, caudolateral to the opening of the main subma.xillary 

 duct, filled one or two small lobules firmly embedded in the mass of 

 the lesser subhngual glands. I consequently believe that the descrip- 

 tion of the older writers is substantially correct when they define the 

 BarthoUnian gland as an occasional alveohngual component, derived 

 from the general group of the lesser or Rivinian subhngual glands, 

 by union of certain glandular components of the latter with the pro- 

 duction of a short common duct draining the separate elements thus 

 combined within the framework of a special gland. 



Conditions encountered in some of the lower mammaha (e.g. 

 Hydrochcerus capyabara, Part VII, page 320) lead me to believe that a 

 further splitting off of a third distinct individual gland, with separate 

 duct, from the general mass of the diffuse lesser subhngual or Rivinian 

 group, may represent an advanced stage in the phylogenetic progress 

 of the lateral alveohngual field, which, as yet, has been attained by 

 only a few types ; but which, if carried further, would develop, in 

 addition to the greater subhngual or Barthohnian gland, a second 



