412 PROCEEDINGS OF THE CANADIAN INSTITUTE. 



separates the fibres into bundles. Both muscular coats may at posi- 

 tions quite change their directions, so as to leave it doubtful if there 

 is more than one coat. Fibrous connective tissue enveloped these 

 on the outside, and on this again is superposed the mesentery. The 

 mucous coat contains coarse connective tissue fibres and has imbedded 

 in it numerous arterial branches which divide and rise under the 

 epithelium layer. Very few lymph corpuscles were observed. 

 Beneath the epithelium the fibres become arranged more densely 

 and give the appearance of a muscularis mucosae. They form a 

 basement on which the epithelium sits. This stratum of densely 

 arranged fibres runs up into minute ridges in which small arterial 

 capillaries and venous capillaries anastomose. 



The epithelium consists in the main portion of the bladder of 

 long cylinder cells, slender, but of larger transverse diametei in its 

 mouth and in the cystic duct. The protoplasm is very finely granular 

 and surrounds a large oval nucleus. The outer peripheral border, 

 easily lost in reagents, does not possess the striation that Yirchow 1 

 describes for other vertebrates. The basal processes are very slender, 

 often divide into two or more branches, and interlace with the fibres 

 of the mucosa. 



In the main portion of the gall-bladder there are but few glandular 

 follicles or crypts. In the arched portion of the duct of the bladder 

 they are much more numerous, and a few may be of such length that 

 a portion of it is bent so as to be parallel with the mucous layer. 

 The cells lining them are cylindrical or rather columnar, which in 

 sections never exhibit a peripheral border, at least it is not manifest 

 in fresh. A cross section of the tubules very often reveals slimy 

 masses in the lumen. The cells do not differ otherwise from those 

 of the general surface, and may have each a peripheral border like 

 them. 



THE PANCREAS. 



For nearly halt a century before 1873 the presence or absence of 

 a pancreas in the Teleost fishes had been one of the disputed ques- 

 tions among anatomists. It may be convenient to go briefly into the 

 history of this dispute, as it led to the discovery ultimately of a true 

 pancreas. 



1 Virchow's Archiv, Bd. XL, page 574. 



