262 DEVELOPMENT OF SALIVARY GLANDS IN THE DOMESTIC CAT 



In the 25 millimeter embryo, No. 147, the inclusion is also on the right 

 side, and has the same appearance in the sections. It is circular, 

 deeply staining except for the pale center, and tapering caudad. In 

 this embryo it hes near the parotid duct, the course of wliich it foUows. 

 Its measurements are : — 



Length, 90 m- 



Distance from parotid attachment, 225 ft. 



Distance from masseteric point, 165 fi. 



In the 28 millimeter embryo. No. 408, the inclusion which is on the 

 left side tapers at both ends. It is solid with a pale center. It follows 

 the line of the buccal sulcus, taking a course that, continued, would be 

 parallel to the orbital sprouts ; for 60 /x it extends caudad of the masse- 

 teric point and lies under cover of the muscle. Its extremity is just 

 craniad and shghtly to the lateral side of the deep facial vein : — 



Length, 100 fx. 



Distance from parotid attachment, 2S0 n. 



In the 51 millimeter embryo. No. 104, the inclusion attains its maxi- 

 mum size for our series. It is on the left side close to the parotid duct, 

 the course of which it follows on its ental aspect. Its cranial extremity 

 is blunt and inflated, containing a lumen for 60 M (Fig. no, 18, 

 page 242). Caudad it narrows abruptly, but is continued as a long, 

 slender object, diminishing gradually to a point. In this portion it is 

 rather poorly and diffusely stained, the cell outlines are indistinct, the 

 nuclei are pale. Its dimensions follow : — 



Length, 273 fx. 



Distance from parotid orifice, 273 ix. 



Distance from masseteric point, 147 ii. 



It remains to consider the occurrence of these several types of orbito- 

 parotid elements a httle more narrowly in reference to the ages of the 

 embryos in which they are present. The sprout in the angular position 

 alone is found in embryos of less than 15 millimeters. It does not 

 occur in any of the series above ig millimeters. If the series is 

 divided into three groups on this basis, the results may be tabulated 

 as follows : 



