312 PROFESSOR FRANK J. COLE 



It will be noticed that Ma as does not regard what I have termed the pharyngeal 

 gut as the cBSophagus, and in this I entirely agree with him. There is something to be 

 said in favour of considering that portion of the gut extending from the ductus 

 oesophago-cutaneus up to the entry of the gut into the abdominal cavity as the true 

 morphological oesophagus. Maas' description of the region, however, does not always 

 agree with what I have found. He describes regular folds, the interior of which is 

 filled with adenoid lacunar connective tissue. I find the folds anteriorly are twice as 

 high as those of the branchial gut, and higher still behind. Their submucosa is very 

 dense and fibrous, and not difi"erent from that of the branchial gut. As regards the 

 epithelium, he says it is layered, but with not so many layers as in the branchial gut ; 

 is in two divisions corresponding to the stratum corneum and stratum Malpighi (the 

 nuclei being difi'erent in these two layers) ; and that there is a striking diminution in 

 the slime cells. In my preparations there are more layers in the epithelium of the 

 "true oesophagus" than in the branchial gut, and Maas' statement only applies to the 

 posterior end. I cannot distinguish the two layers, nor in fact any essential difference 

 between the epithelium of the oesophagus and the branchial gut, in both of which the 

 glassy and granular mucous cells are very abundant. Posteriorly, however, the 

 granular cells are greatly reduced in number, although the glassy cells are still present 

 in quantity. The superficial cells here give the mucin reaction, and the epithelium is 

 more like that figured by Maas. I find no trace of the muscularis mucosae described 

 by Maas, but the unstriped circular musculature is very well marked. Maas' striped 

 musculature is, of course, the constrictor cardia3, and does not belong to the intrinsic 

 musculature of the gut. 



I see no grounds for regarding that part of the gut which extends from the entrance 

 of the gut into the body cavity up to the opening of the bile duct as a stomach. The 

 bile duct does not coincide with any change in the structure of the gut, and therefore 

 to use it as a boundary is entirely arbitrary. Maas gives the characters of this part 

 of the gut as follows : Epithelium single-layered, with striated border and- no pits. 

 Gland cells and mitoses present, also a muscularis mucosae. Adenoid submucosa 

 with large vessels. Circular unstriated musculature. In my preparations the striated 

 border and gland cells are not present at the anterior end of the "stomach," but 

 epithelial pits do occur in this region of the gut. I find no muscularis mucosae, and 

 the submucosa in every sense connects up the dense fibrous submucosa of the 

 oesophagus with the stratum compactum of the abdominal gut. 



ScHREiNER divides the. gut of Myxine into a mouth, oesophagus [pharyngeal gut], 

 intermediate region (no stomach), true gut, and ectodermal anus and cloaca. In the 

 mouth he finds the epithelium many-layered, the superficial layer giving the slime 

 reaction, and the basal cells being small and polygonal. The slime cells, the life of 

 which terminates with the discharge of the slime, are exactly similar to those of the 

 skin, and develop in the same way. There are no granular cells. The boundary 

 between the mouth and "oesophagus" is the naso-pharyngeal opening. In the "inter- 



