GENESIS OF NASOLACRIMAL PASSAGES IN MAN 5 



ing to Fleisher, depending upon the form studied, came to the 

 conclusion that one of the two lacrimal ducts was wholly or partly 

 a portion of the original mother cord of cells, and that the other 

 lacrimal duct and the remaining portion of the nasolacrimal duct 

 developed as sprouts from the mother cord. 



Hammar ('02) shows a model' of a human embryo 18.5 mm. 

 long in which both the nasal and ocular ends of the anlage of the 

 nasolacrimal passages are free from the surface epithelium. The 

 anlages of the lacrimal ducts are well illustrated in the model. 



Fleisher ('06) published his researches on the pig, the guinea 

 pig, the mouse, the rabbit, and man. He arrived at the follow- 

 ing general conclusion: 



Aus diesen Praparaten geht hervor, dass beim Menschen die Ent- 

 wicklung der Tranenrohrchen in derselben Weise vor sich geht, wie 

 bei den anderen, von mir untersuchten Saugetieren, durch selbstandige 

 Sprossung jedes der Rorchen aus dem Augenende der Tranenleiste, 

 die sich vollstandig vom Epithel abschnurt. 



Fleisher, therefore, disagrees with Legal and some others on the 

 genesis of the lacrimal ducts (lachrymal canaliculi) , and conforms 

 with Kolliker and more nearly to Ewetzky. He is also in accord 

 with Matys who came to similar conclusions for Spermophillus 

 citillus. 



Lang ('11) reports his findings in a human embryo, aged from 

 seven to eight weeks. He finds that the left side of his embryo 

 agrees with the conclusions of Fleisher and Matys. On the right 

 side he, however, finds the superior lacrimal-duct anlage wanting. 



In subsequent portions of this paper I wish to record my pre- 

 liminary observations on the genesis and development of the 

 nasolacrimal passages in man. I now hope to carry this study 

 farther and, if an investigation of a larger number of human 

 embryos warrants, will report my later observations and con- 

 clusions in a subsequent paper. 



In looking over material for the substance of another paper 

 I noticed variations in the development of some portions of the 



3 Studien iiber die Entwicklung des Vorderdarms und einiger angrenzenden 

 Organe, Archiv f. mikrosk. Anat., Bd. 59, taf. 26, fig. 14. 



