246 DEVELOPMENT OF SALIVARY GLANDS IN THE DOMESTIC CAT 



therefore, been made to establish a rigid chronology of the growth of 

 the sprout. The path followed extends along the sloping border of the 

 masseter nearly to its ventral limit. Just before reaching this, how- 

 ever, it turns to the lateral surface of the muscle near, but not actually 

 at the ventral margin. It now grows horizontally caudad until the 

 caudal border is reached. Here the secondary branches are directed 

 dorsad as well as caudad towards the cartilage of the external auditory 

 meatus. This position of the duct may be termed inframuscular, 

 the definitive position in ungulates. 



The surface of the masseter where the duct lies against it is faintly 

 grooved. About the enlarged fundus of the bud the mesenchyme is 

 slightly thickened and shows a concentric arrangement of its elements. 

 After the sprouts of the second and third order have appeared, a very 

 slight change of like nature can be observed about them, and the same 

 is true of late stages when the branches have become numerous. The 

 degree of thickening is so small that with a low power the branches 

 seem to lie free in an almost unaltered mesenchyme, in marked contrast 

 to those of the submaxillary and greater subhngual gland, which are 

 surrounded by a conspicuous and well-circumscribed condensation. In 

 part this may be explained by the relatively small bulk of the parotid, 

 which markedly lags behind the submaxillary in development, but it 

 can hardly be entirely so accounted for. In the adult the parotid has 

 a far looser structure and lacks a capsule in the strict sense of the term. 



The secondary sprouts appear as small knoblike irregularities of 

 the surface of the enlarged extremity of the primary bud. They are 

 regularly present in the 18 millimeter embryos, when the growth has 

 reached the sagittal midtliird of the muscle. In some of these the 

 secondary sprouts have attained a length of 20-40 ^. These branches 

 are not numerous (5-7) ; they are directed at first caudad, continuing 

 the fine of the duct. In a few cases in wliich they were studied they 

 were found to vary in number and arrangement, not only from embryo 

 to embryo, but from side to side of the same embryo. In the 25 

 millimeter embryo the branches are retromasseteric and pointing 

 dorsad towards the ear. 



Recurrent branches of the parotid were present in two embryos, 

 arising from the anlage of the duct immediately in front of its division. 

 In the 20 millimeter embryo. No. 83 (Fig. 104, gg), on the left side a 



