630 Jacob Parsons Schaeffer. 



really due to septal tissue. This fold is the anlage of the conchae 

 nasales ethmoidales, and in position and relations represents the 

 concha nasalis media (Ethmoturbinale I, Peter; zweite Haupt- 

 muschel, Killian; untere Siebbeinmuschel, Zuckerkandl; Basotur- 

 binale, Schonemann). The fold of the agger nasi (nasoturbinal) 

 can hardly be said to be in evidence at this early stage. It appears 

 later, ventral and superior to the concha nasalis inferior, and ven- 

 tral to the concha nasalis media. 



Views as to the genesis of the primitive nasal folds and furrows 



From the above we gather that the lateral nasal wall is early 

 thrown into ridges or folds which are bordered by furrows or 

 depressions. Just how these primitive folds (primitive conchae) 

 and furrows (primitive meatuses) of the lateral wall are formed 

 is interpreted differently by various writers. While at first 

 thought the views held seem widely divergent, they appear less 

 so after we carefully analyze them. Some of the theories enter- 

 tained are, however, without foundation. 



It was at one time held by some observers that the folds were 

 due to cartilaginous strands pushing the lateral nasal wall medi- 

 ally in the positions of the folds. This theory is, however, not 

 tenable because the folds (primitive conchae) are invariably 

 present some time before cartilage is found in them. Only later 

 does some of the indifferent mesenchyme contained in the folds 

 change into cartilage ; therefore it can have no connection whatever 

 with the establishment of the primitive folds (conchae). 



Legal and Schonemann think that the folds are elevations left 

 by excavations of furrows on the lateral nasal wall. Legal in 

 offering this explanation especially referred to the inferior nasal 

 concha. Later Schonemann concludes ''dass nicht die Legalsche 

 Angabe iiber die Bildung der unteren Muschel vollig zu Recht 

 besteht, sondern dass auch fiir die samtlichen anderen Muscheln 

 ein ahnhcher Bildungsmodus angenommen werden muss." 



Mihalkovics, according to Schonemann, holds that the folds 

 are at first "frei vorwachsende Duplikaturen der Schleimhaut." 

 Glas, who investigated this field in rats, comes to the following 



