PRIMATE ALVEOLINGUAL SALIVARY AREA 125 



tive uniform anlage for further development may retain the earlier 

 character as collections of separate individual glands, each possessing 

 a distinct opening upon the oral mucosa. The border fields along 

 the sagittal lines / and A' are especially so characterized, forming 

 cephalocaudal series of simple glands, only interrupted at the coronal 

 cleavage level F. 



It is, however, possible that in certain areas portions of the available 

 anlages of a definite district unite to form a conducting canal, while 

 the remainder develop the secreting glandular mass draining into the 

 same. 



Thus, in the cephalic division in Fig. 4, the two elements A* and B^ 

 of sagittal line IV may unite and acquire a lumen forming a duct for the 

 secreting gland produced by continued development of the nine primi- 

 tive anlages, C'*'^',!)''^'^ and£^'^'^. The whole intermandibular salivary 

 apparatus in such a case will then differentiate into a complete com- 

 pound gland {b) whose body and duct are embedded among the ad- 

 jacent masses of individual simple glands, which in turn are separated 

 from each other by the Unes along which glandular development was 

 suppressed. 



This general type of intermandibular glandular distribution finds 

 representation among adult vertebrates in a few forms (reptilian) in 

 which "anterior" and "posterior" "sublingual glands" are distin- 

 guished. 



Among the mammalia the chief lines, along which segmentation 

 of the primitive uniform glandiferous field of the oral floor takes 

 place, are sagittal, resulting in the formation of a series of cephalo- 

 caudally directed glandular integers, separated from each other 

 by the intervening sagittal strips of mucosa in which gland devel- 

 opment is suppressed. This prevailing mammalian type may be 

 carried through consistently, or may be varied by combinations 

 in which the main sagittal segmentation lines of glandular suppres- 

 sion are interrupted by the partial preservation of coronal lines of 

 glandular retention and further development, thus joining elements 

 of adjacent sagittal gland areas to each other in a great variety of 

 types. 



Further, the mammalian alveolingual gland field is characterized by 

 the retention along its lateral boundary (alveolar border) of the primi- 



