DEVELOPMENT OF HUMAN PHARYNX 341 



the accompanying simple diagrams (schema A). Such an inter- 

 pretation was essentially set forth by His ('85), as would appear 

 from his well-known view of the origin of the so-called 'lateral 

 thyreoid.' However one is incUned to interpret the origin of 

 the lungs — as primarily developed out of and representing bran- 



chial pouches and hence primitively double in origin, or as aris- 

 ing caudad of the branchial region and appearing as a medial 

 ventral outpocketing of the pharyngeal entoderm caudad of 

 the branchial region^ — its morphological position is caudal to the 

 branchial portion of the pharynx as developed in the higher verte- 

 brates. The position of the laryngeal opening in the pharynx 

 is in the nature of an intrusion, due in part, as has already 

 been stated, to its precocious appearance, affecting thus markedly 

 the essential morphology of the developing pharynx. It is not, 

 I believe, going too far to interpret the 'furcula' described by 

 His ('85) and shown in his well-known and often reproduced 

 figures (40) as itself but a fold due to the interrelated growth of 

 glottideal lips and branchial pharynx and in itself, therefore, 

 of no intrinsic morphologic significance. 



How early the tracheo-pulmonary outpocketing makes its 

 appearance it is difficult to determine. Grosser's ('11) account 

 is the most satisfactory, although clearly other embryos of about 

 this stage (Robert Meyer embryo No. 300) and earlier should 

 be examined. With the mid- ventral groove (ventral pharyn- 



