DEVELOPMENT OF THE ALIMENTARY TUBE AND APPENDED ORGANS. 327 



frequent, apart from transposition, include anomalies in the size and number of 

 lobes. Accessory lobes may occur within the falciform ligament. One case 

 of lack of development of the gall bladder has been observed. Stenosis of the 

 bile passages is occasionally met with. 



THE PANCREAS. Occasionally accessory glands are found in the intesti- 

 nal or gastric wall. These probably represent aberrant portions of the main 

 gland, and may give rise to cystic structures. Very recently, however, a 

 number of intestinal diverticula have been observed in certain mammalian 

 embryos and also in human embryos. Although the history of these unusual 

 diverticula has not been traced, their presence may offer a clue to the origin of 

 accessory pancreatic structures. The ducts of the pancreas are subject to 

 distinct variations, which, however, are not usually considered as anomalies. 

 Not infrequently the duct of the dorsal anlage (duct of Santorini) persists and 

 opens directly into the duodenum. It may persist along with the duct of the 

 ventral anlage (duct of Wirsung), or the latter may disappear (p. 321; compare 

 Figs. 2 78 and 279). 



References for Further Study. 



BADERTSCHER, J. A. : The Development of the Thymus in the Pig. I, Morphogenesis. 

 II, Histogenesis. Am. Jour, of Anat., Vol. XVII, 1915. 



BARDEEN, C. R.: The Critical Period in the Development of the Intestines. Am. 

 Jour, of Anat., Vol. XVI, 1914. 



BELL, E. T.: The Development of the Thymus. American Jour, of Anat., Vol. V, 

 1906. 



BERRY, J. M.: On the Development of the Villi of the Human Intestine. Anat. Anz., 

 Bd. XVI, 1900. 



BONNET, R.: Lehrbuch der Entwickelungsgeschichte. Berlin, 1907. 



BORN, G.: Ueber die Derivate der embryonalen Schlundbogen und Schlundspalten bei 

 Saugetiere. Arch.}, mik. Anat., Bd. XXII, 1883. 



BRACKET, A. : Die Entwickelung und Histogenese der Leber und des Pancreas. Ergeb- 

 nisse der Anat. u. Entwick., Bd. VI, 1897. 



CHIEVITZ, J. C.: Beitrage zur Entwickelungsgeschichte der Speicheldriisen. Arch. f. 

 Anat. u. Physiol., Anat. Abth., 1885. 



CHORONSCHITZKY: Die Entstehung der Milz, Leber, Gallenblase, Bauchspeicheldruse 

 und des Pfortadersyssems bei den verschiedenen Abteilungen der Wirbeltiere. Anat. 

 Hefte, Bd. XIII, 1900. 



Fox, H.: The Pharyngeal Pouches and their Derivatives in the Mammalia. Am. 

 Jour, of Anat., Vol. VIII, No. 3, 1908. 



FUSARI, R.: Sur les phenomenes, que Ton observe dans la muqueuse du canal digestif 

 durant le developement du fcetus humain. Arch. ital. Biol., T. XLII, 1904. 



GOPPERT, E.: Die Entwickelung des Mundes und der Mundhohle mit Driisen und 

 Zunge; die Entwickelung der Schwimmblase, der Lunge und des Kehlkopfes der Wirbeltiere. 

 In Hertwig's Handbuch der vergleich. u. experiment. Entwickelungslehre der Wirbeltiere. 

 Bd. II, Teil I, 1902. 



