DEVELOPMENT OF THE LARGE INTESTINE 211 



Noch erlibrigt es mir, die Art unci Weise anzugeben, wie sich die 

 Lieberkiihn'schen Driisen vermehren. Bei der Durchsicht der Prapa- 

 rate, hauptsachlich aus den alteren Stadien, findet man oft im Grunde 

 etwas verbreiterte Driisen. In der Mitte des verbreiterten Grundes 

 erhebt sich ein Epithelliockerchen. Oft auch ist dieses Hockerchen 

 nicht mehr bios aus Epithelzellen gebildet, sondern gleicht im Durch- 

 schnitte einem mit Epithel liberkleideten Zottchen, welches in das 

 Innere der Drlise hineinragt. Es entspricht dem Durchschnitte eines 

 kleinen Faltchens, welches den Grund der Druse in zwei Theile spaltet. 

 Dieses Faltchen wachst immer hoher und hoher. Die Driise hat 

 endlich das Aussehen^ als ob in einem gemeinsamen Vorraum zwei Drii- 

 senschlauche miindeten (Fig. 29 e). Wenn schliesslich die Hohe des 

 Faltchens in gleicher Ebene mit der Innenflache des Darmes steht, ist 

 der Theilungsprocess vollendet, es sind aus einer Driise zwei geworden. 



He further believes that the upward growing connective tissue 

 papilla continues its upward growth after it reaches the surface 

 level and thus gives rise to a new villus. 



In further support of Patzelt's view regarding gland multi- 

 plication may be mentioned that if new glands appeared as 

 new outward growths from the epithelium, then one would 

 expect to find always in any fetal intestine glands w^hich extended 

 for varying distances toward the muscularis mucosae. How- 

 ever, such an appearance is never found. The basal ends of 

 the glands, as seen in figures 5, 6, 7, 8, 24 and 25, all extend 

 down to one general level, no intermediate lengths being present. 

 The branched types of glands are always present, some with 

 two, some with three, and some with even four divisions. The 

 amount of bifurcation also varies as Patzelt has figured. As 

 in all problems of growing structures, it is indeed difficult to 

 say precisely what changes are taking place, but I believe it 

 safe to say that in this case that additional glands are developed 

 by a longitudinal splitting of those already present. 



In the transverse colon of an embryo of 200 mm. practically 

 the same conditions as those described for the sigmoid colon of 

 the 190 mm. stage are encountered. The mucous membrane, 

 although not thrown up into folds, does not appear stretched 

 out. The villi are of various sizes, the tallest being from 0.14 

 to 0.18 mm. high. The intestinal glands measure from 0.18 to 

 0.22 mm. in length. Other measurements taken are as follows: 



THE AMERICAN JOTJHNAI- OF ANATOMY, VOL. 14, NO. 2 



