MAMMALIAN ALVEOLINGUAL SALIVARY AREA 345 



the early condition of the sublingualis major, and especially the 

 nature of its relation to the submaxillary. Through the kindness of 

 Professor C. F. W. McClure, who permitted me to make use of the 

 beautiful embryos of the Princeton Collection, I have been able to 

 secure the necessary data to demonstrate the primitive indejiendence 

 of the sublingualis major, and its displacement mesad with the forma- 

 tion of the submaxillary flange, to the lateral lamina of which it is for 

 a time attached. 



In a pig of 15 milhmeters (Princeton Collection, No. 211) the sub- 

 maxillary anlage alone is present. The Hngual sulcus has deep cranial 

 and caudal segments, corresponding respectively to the regions of the 

 frenulum and of the submaxillary ganglion, which are connected by a 

 shallower intermediate portion. In its whole extent its epithelium is 

 thickened slightly at the fundus. While thus agreeing in general con- 

 formation with that of the cat, the lingual sulcus of the pig is charac- 

 terized by its great depth caudal to the lingual nerve (Fig. 2,4). Here 

 it is an open V-shaped furrow directed ventrad and shghtly laterad in 

 the sections. Its lateral wall passes at a rounded, but nearly right, 

 angle into the floor of the alveolingual region. The thickened epithe- 

 lium of the fundus assumes the form of a small keel at the hngual cross- 

 ing (7), which, increasing in size, attains a maximum 120 /it caudal to 

 the nerve and thence diminishes as gradually, but can be followed as 

 far as the origin of the first entodermal pouch. In its sections of maxi- 

 mum size the epithehum of the submaxillary anlage is slightly con- 

 stricted at its junction with the lingual sulcus. A periderm layer is 

 everywhere present in the mouth, but cannot be followed into the 

 anlage ; the fundus of the sulcus, while acute, does not show clear evi- 

 dence of compression. If the anlage is interpreted as due to enlarge- 

 ment of the submaxillary keel, that is, as the result of a process of pro- 

 liferation, in toto in this stage, as far dorsad as the constriction in 

 subsequent stages, no gross error will be made ; but it is difllcult, if not 

 impossible, to make an absolute distinction between flange and prolif- 

 eration in the pig, because the staining properties of periderm and 

 basal cells are so nearly identical that the former cannot be recognized 

 with certainty in the fully formed flange. Such a deep open lingual 

 sulcus as here affords attachment to the submaxillary proliferation is 

 never seen in the cat, in which a flange is present before the prolifera- 



