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the liver, orticiates as an organ with internal secretion. The excretory 

 ducts of these glands, as well as the gall-bladder, have disappeared 

 after the metamorphosis, but in the Ammoc.oetes, the larva of the 

 Lampreys, they are present. 



The pancreatic gland of Ammocoetes lies hidden in the wall of 

 the gut on the left side of the excretory duct of the liver. 



At a quite analogous place I found the gland in Amphioxus from 

 the first appearance of the liver in the period of the metamorphosis 

 until the adult form. With good nuclear staining it can be seen, in 

 preparations in toto of (he newly metamorphosed larva, as a trian- 

 gular stain on the left side of the wall of the gut immediately behind 

 the place where the blind sac of the liver emerges. The rounded 

 top of the triangle points forwards, the base is a transverse line, 

 crossing the longitudinal axis of the animal at right angles. With a 

 strong magnification it can be seen, more clearly still in cross section, 

 that we have to do with a slight emergence of the wall of the gut. 



In the sections we see that the gland possesses a strong ciliary 

 epithelium, but it has moreover cells without ciliae which may be 

 considered as the true glandular cells. In the adult animal the gland 

 is stretched more longitudinally, and consequently the emergence of 

 the gut wall is a longitudinal fold; its fore-end has been taken up 

 in the hiud-end of the blind liver sac. We find an analogous 

 phenomenon in some fishes, where the pancreas is partly enveloped 

 by the liver. 



The reason why the numerous investigators of (he anatomy of 

 Amphioxus could not find a pancreas is easily given. The mid-gut 

 epithelium presents in cross section so msiwy folds *) that it cannot 

 be expected that one could distinguish these from the pancreatic fold 

 unless one's attention has been drawn to this in young animals. 



In the ontogenesis of the Craniota the liver (as an emergence of 

 the gut) is first recognisable; somewhat later also the pancreatic 

 gland. In Amphioxus this is just reversed. While the liver first 

 makes its appearance as an emergence of the gut in the period of 

 metamorphosis, the j)ancreatic gland can be followed back to the 

 stage with two open gill clefts (in larvae with only one gill cleft 

 it could not be seen). It is originally not limited to the left side, as 

 is later the case, but envelops the gut like a ring. The ring is 

 recognisable in tliat its nuclei are smaller and placed closer together 



1) These folds are also found in the oesophagus, (whose hind-end corresponds 

 morphologically to the stomach of the higher animals\ and in the foremost por- 

 tion of the end-gut. They serve for enlarging the resorbant surface. In young 

 animals they are not present. 



