182 ANATOMY OF THE SALIVARY GLANDS IN THE CARNIVORA 



in late stages of development orbitoparoti.d sprouts may be formed 

 directly from the oral epithelium, for their frequency increases in the 

 larger embryos, and to judge from the conditions in the adult they may 

 arise in later periods from the promasseteric portion of the parotid 

 duct. On the other hand, in two embryos only, on one side in each, 

 were sprouts found in the transmuscular segment of the duct. They 

 were ventrally directed and close to the point where the duct divided, 

 a small proximal bud, and a slender recurrent branch, corresponding 

 in general disposition to the lobules 6 and 7 of Fig. 5. No other 

 derivatives of the duct have been recorded in embryos of the cat. 



The extension of the parotid along its duct attains its highest devel- 

 opment in Gulo, where it extends to the border of the masseter and 

 is dorsal in position. Accessory- lobules representing a less degree of 

 this process have been found in Canis (dorsal and ventral), in Felis 

 (ventral only), and in Taxidea (a minute dorsal lobule). The ventral 

 angle of the gland is frequently of loose structure and manifests a 

 tendency to resolve itself into independent lobules. The duct also 

 varies in its emergence, being sometimes single, sometimes in two or 

 several branches, and these variations occur in individuals of the same 

 species and often on the two sides of the same individual (dog and 

 cat). The ventral angle may be suppressed (lioness) and the duct 

 emerge abruptly from the body of the gland, or the duct may continue 

 undivided in the gland substance for a considerable distance (sea- 

 lion). In consequence of these frequent variants the transition 

 between circumductular portion and body (sensit striclo) is far less 

 definite in the parotid than in the submaxillary, while in the sublin- 

 gualis major, on the other hand, the two portions are often not recog- 

 nizable externally. 



Apart from these conditions at the hilus, and in contrast to the 

 extensions along the ducts, the bodies of the glands seem to be subject 

 to little variation in the species where sufficient material has been 

 available for comparison. Their shape bears a direct relation to their 

 size, in that this determines the degree of their contact with, and conse- 

 quent adaptation to, their topographical environment. As this is 

 different for each gland, each has a characteristic form impressed upon 

 it, which can be referred to definite factors. We may take as the prim- 

 itive form of all these glands an elongated ovoid, rounded distad. 



