PRIMATE ALVEOLINGUAL SALIVARY AREA 137 



III. Detailed Analysis of the Adult Primate Sub- and 

 Inter-mandibular Salivary Complex on the Basis of 

 the Preceding Genetic Theory 



A study of the individual primate adult forms previously described, 

 on the basis of the genetic interpretation just outlined, is, perhaps, best 

 undertaken without reference to the zoological position of the species 

 considered. Tliis procedure has the double advantage of allowing 

 variants (chiefly human) to be grouped with other primate types along 

 morphogenetic Hnes, and of accentuating the plasticity of the alveo- 

 hngual area in a developmental sense by direct comparison of adult 

 t^-pes derived from individual examples of widely separated zoological 

 primate genera. 



It may, however, be appropriate at this point to clearly define the 

 meaning of the analytical study of primate alveolingual salivary 

 organization. 



From what has already been said the inference might be drawn that 

 the arrangement of the glands in any given adult indi\adual is a mat- 

 ter of pure chance in selection of one developmental route out of the 

 many oiifered, and that in consequence the actual individual type of 

 glandular organization is of no morphological and phylogenetic sig- 

 nificance. Tliis is by no means the case. We are dealing here with 

 conditions which, for example, are repeated in the development of the 

 postrenal segment of the postcaval vein in the cat. In this latter 

 instance a uniform and comprehensive groundplan of available peri- 

 aortal axial venous channels is actually provided in every embryo. In 

 the course of what we regard as normal and typical development, the 

 majority of indi\'iduals select one of these numerous available hydro- 

 static lines, the right supracardinal, for further development into the 

 adult vessel. This particular vascular area of the cat is, however, 

 signalized by a very extensive range of primary adult variations. 

 Each of the variants recorded in a large series of adult animals fits 

 accurately into the framework of genetic possibihties offered by every 

 embryo in the earher stages. Consequently, we are in this case ab- 

 solved from the necessity of going beyond an ontogenetic explanation 

 of recorded adult variants. They all show clearly the embryonic 

 selection of an available venous pathway, which is not so used by the 



