I J. PARSONS SCHAEFFER 



passages, but does not state his meaning clearly. 2 He apparently 

 thought that the nasolacrimal passages had their origin in a 

 diverticulum or skin-fold ('Hautfalte') in the region of the medial 

 palpebral commissure (internal canthus) and, since the naso- 

 optic fissure is obliterated by the eighth week of embryonal life, 

 he must have thought that the 'Hautfalte' grew into the sub- 

 stance of the maxilla, ultimately reaching the nasal cavity. Bur- 

 dach may have had the right conception of the development of 

 the nasal end of the nasolacrimal duct, but in the genesis of the 

 nasolacrimal passages from a skin-fold ('Hautfalte') in the region 

 of the medial palpebral commissure he erred (providing the writer 

 interprets his statement correctly). It is difficult to say what 

 Burdach meant by his 'Hautfalte.' That the anlage of these 

 passages comes to lie in the body of the maxilla is true, but it 

 comes about in an entirely different way as will be seen subse- 

 quently. His theory would not explain the origin of the paired 

 lacrimal ducts. 



Erdl ('45) and Coste ('47-59), according to Ewetzky, believed 

 that the furrow "welche am Naseneingange beginnt und am 

 inneren Augenwinkel miindet, auf ihrer ganzen Lange iiber- 

 briickt und dergestalt in einem Canal verwandelt." That the 

 naso-optic fissure becomes constricted or shut off from the sur- 

 face by its lips closing in and coalescing with each other, thus 

 establishing the nasolacrimal connections, was indeed the accepted 

 theory for some time. The theory is, of course, erroneous because 

 the anlage of the passages is for some time represented by a solid 

 plug or strand of epithelial cells which early becomes detached from 

 the surface. The strand of cells becomes cord-like and acquires 

 a lumen secondarily (see subsequent paragraphs) . Neither would 

 this theory explain the pairing of the lacrimal ducts. 



So far as my review of the literature would prove, Born (76) 

 was the first investigator to properly interpret the earliest stages 



2 Der innere Augenwinkel is1 mehr verlangert als bei Erwachsenen und stent 

 tiefer als der aussere; schon in der achten Woche erscheint in ihm die Karunkel 

 und eine zur Mudnasenhohle sich sekende Hautfalte als Anfang des Thranenkanals. 

 Die Thranenpunkte ragen im funften Monat sehr stark hervor und im siebenten 

 ctwas mehr zurtick. 



