332 MAMMALL4N ALVEOLINGUAL SALR'.\RY AREA 



oritices, but the mode of this shift is not described. The presence of 

 the sublingualis major and its numerous side branches is noted in the 

 dog and pig. In a figure taken from a rodent embryo of 51 miUimeters 

 (he calls it a mouse, but has evidently confused his material as Cliievitz 

 pointed out) he shows the elements in their adult relations, the lesser 

 subhnguals dorsal, then the sublinguahs major, and ventrally the 

 submaxillary. Finally, in a rabbit embryo of 56 milhmeters he states 

 that all three elements are present, and on this observation founds his 

 inference that the anlages are constant, but that that of the subhnguaUs 

 major may be suppressed in later stages. Chievitz fomid no Barthohn- 

 ian element in the rabbit, and suggested that Reichel had mistaken for 

 it the most anterior of the lesser sublinguals, an error which his descrip- 

 tion of the mouse embryo shows he had no means of avoiding. The 

 explanation of this is difficult only if we assume that the "rather 

 young" embryo in question was what a modern investigator would so 

 designate. Reichel seems to have had — at least he reported — no 

 very young embryos. Assuming the mouse in question to have ad- 

 vanced considerably in development, the description is comprehensible, 

 which it certainly is not, if it be taken to apply to an early stage. On 

 this assumption the lateral furrow beside the tongue would be the 

 sulcus circumflexus, which limits the plica sublingualis in front and 

 at the side. This appears in man and in the cat before the ducts 

 reach the transverse plane of the frenulum, and the Bartholinian duct 

 is attached to the plica near, but not actually in, the circumflex sulcus. 

 In man and the cat this furrow gives origin to the early sprouts of the 

 diffuse Rivinian glands, in man close to, in the cat far caudal to, the 

 attachment of the Bartholinian duct. In later stages the number of 

 these glands is increased by sprouts of more mesal position, from the 

 surface of the plica sublingualis (Chievitz), from the lingual sulcus 

 itself (Reichel), and in forms in which the lesser subhnguals become 

 continuous with the isthmian group, additional elements must be 

 formed from the oral epitheHum mesal to this sulcus. This condition 

 has not yet been reported in an embryo. It is not, therefore, neces- 

 sary to accuse Reichel of an error of observation in his assignment of 

 the lesser sublinguals to a position caudal to the attachment of the 

 anlages of the larger glands, but it is unfortunate that the length of 

 this embrvo was not stated. 



