22 2 DEVELOPMENT OF SALIVARY GLANDS IN THE DOMESTIC CAT 



pars lata seems rather to diminish in section and eventually cannot 

 be distinguished from the pars cyUndrica. In one of the i8 millimeters 

 embryos (Fig. 97) it can scarcely be recognized. However, it usually 

 is clearly marked up to 28 millimeters. In the later stages (Figs. 107, 

 log, 114) the whole inclusion appears of about the same diameter. 



The cranial process may be very long and tapering after separation, 

 in embryos of i8~20 millimeters extending not rarely to the deep facial 

 vein and occasionally craniad of it. Its position is such cases is indi- 

 cated in Fig. 102 (dotted circle below 20, not leadered). In embrj'os 

 of more than 20 millimeters this tapering form is rare and the inclusion 

 ends caudad of the vein, at an interval increasing in later stages. The 

 cranial process is exceedingly variable in length, so that it cannot 

 positively be asserted of these short forms that they were longer at an 

 earher period, yet it seems probable that atrophy has here occurred, 

 and that the pressure of the facial vein may play a role in its causation. 



The lateral process never attains a large size. The one in the 

 15 milHmeter embrj'o (Fig. 44) is a fair example of its ma.ximum. It 

 is a blunt or conical projection from the pars lata, lateral to the bucco- 

 masseteric nerve, varying in length from 13 /^ to 36 M- It is not always 

 present (Figs. 45, 97). It never attains the retortlike shape of an 

 active sprout, and in many cases it is hard to satisfy one's self that it is 

 more than the bulging of the pars lata, which is pressed against the buc- 

 comasseteric nerve. This contact is absolute in embrj^os of 13.5 to 

 15 milUmeters, no mesenchjTne intervening. After the separation 

 of the inclusion, the lateral process soon disappears and is not present 

 in any embryo of greater length than 22 milhmeters. Here, as in the 

 processus caudahs, the tendency to sprouting is very feeble in the cat. 



It has been said that the displacement of the inclusion with refer- 

 ence to the secondary buccal sulcus is at first ventral and lateral. The 

 latter direction is retained throughout the period covered by our 

 series. The direction of the vertical displacement is reversed in later 

 stages when, with the enlargement of the jaw and the muscles of mas- 

 tication, the inclusion comes to occupy a more dorsal position. In 

 the embryos of 28 millimeters and 7,^ milUmeters it hes at about the 

 level of the secondary buccal sulcus. In those of 51 milhmeters and 

 70 millimeters (Figs. 109, 114) it is placed dorsal to the sulcus, except 

 for its caudal extremity, which turns ventrad, in the case of the 51 



