350 m.4Mm:.a.lian al\'EOlingual salivary area 



not argue against the interpretation of its position here also as secon- 

 dary. At the same time if an inrolling incident to the formation of 

 the submaxillary- flange occurs, and the evidence seems ample that it 

 does, it is clear that the site of the anlage of the sublinguaUs major will 

 depend upon the rate of the inrolling and the time at which this 

 proHferation begins. It is, therefore, abstractly possible that in cases 

 where a considerable degree of inrolUng occurs, or where the sub- 

 hnguals major is late in initiating its proUferation, the anlage might 

 appear primarily attached to the flange of the subma.xillary, but none 

 the less would its epitheUum be of lateral provenience. There is no 

 chfficulty, on the evidence afforded by the mouse, cat, and pig, in 

 interpreting the sublingualis major as an independent derivative 

 of the alveohngual epithehum, characterized by the intermediate 

 position of its anlage and duct, between those of the subma.xillary and 

 of the lesser subhngual glands. 



Two types of de\-elopment of the sublingualis major may, therefore, 

 be defined on the basis of our present knowledge : — 



1. The anlage appears as a proHferation crest attached to the 

 alveolingual epithelium, lateral to the lingual sulcus and the anlage 

 of the submaxillary, from which it is separate and absolutely indepen- 

 dent throughout development. This tj^pe occurs in the cat, and, ap- 

 parently, in the mouse (Reichel, Chievitz, Goppert). 



2. The anlage arising in the same way becomes approximated 

 to that of the subma.xillary secondarily, being displaced mesad and 

 drawn into the flange of the larger gland. It is to be noted that in 

 this case it is attached to the flange, and not to the keel of proliferation 

 which forms its free border. In front of the flange it too advances by 

 means of a keel, and has an independent attachment to the Ungual 

 sulcus. Wlien the sulcus is obhterated, a common flange is formed, 

 along which both submaxillary and subungualis major advance inde- 

 pendently. This t}pe is found in the pig ; it is Ukely that it also 

 occurs in man, but as yet the evidence is incomplete. 



The relation of the anlage of the BarthoUnian element to the flange 

 of the submaxillary does not directly determine the nature of its 

 definitive debouchment, whether into the duct of the subma.xiUar}- or 

 by an independent orifice, nor is it possible at present to estimate the 

 factors which effect this difference. In both man and the pig the 



