I06 SALIVARY GLAXDS OF LOWER PRIMATES 



the adult organs grow from the initial anlage caudad by further exten- 

 sion and proliferation of the glandular epithelium, the intraglandular 

 duct system developing by subsequent canalization of primarily 

 solid branching epithehal cyUnders. 



2. On the other hand, the extraglandular excretory ducts of the 

 submaxillar^' and greater sublingual components are developed as 

 proliferating epithelial keels which extend cephalad from the primitive 

 anlage and subsequently acquire a lumen. These may in later stages 

 give rise to accessory glandular sprouts. 



In comparing the lower primate species here described it becomes 

 apparent that the indi\'idual conditions can be interpreted with the 

 aid of our available ontogenetic data on the plan of the composite 

 scheme shown in Fig. 26. 



The entire floor of the mouth, between tongue and alveolar border 

 of mandible, can be divided into three potential glandular districts 

 in the broad sense, including in the term both the development of 

 gland tissue and the formation of duct canals. 



The most lateral of these districts (j) is purely glandular in its 

 results, and jnelds the constant primate component of the entire 

 group which, since Chievitz's investigations, has been known as the 

 alveolingual complex, consisting of a varying number of individual 

 glands, opening by separate orifices along the crest of the alveo- 

 lingual ridge. This component is here described as the collection 

 of the lesser sublingual glands. 



The most medial district (7) is also constantly responsible for 

 primate glandular development, and forms the largest, and, in its 

 details of structure, the most variable, component of the entire 

 group. 



It can be divided into three secondary areas, 7, 7', and i" . 



I represents the hne of development of the main subma.xillary 

 gland and duct. Both gland and duct may be simple and single, 

 as above described. 



This medial alveolingual district, forming thus the site of develop- 

 ment of the main submaxillary gland and duct, exhibits additional 

 potential genetic characters. 



Thus the epithehal crest which forms the anlage of the main duct 

 is capable of yielding, by more or less complete subdivision, a secon- 



