238 THE SOLIDS. 



scribed kind; that is, they consist of nucleus, cell wall, 

 granules, and fluid contents: the chief difference is one of 

 form and not of structure. 



The nucleus is almost invariably oval, the long axis corre- 

 sponding with that of the cell itself : it is often so large as to 

 occasion the cell to assume a ventricose form, it being con- 

 tracted immediately above and below the part in which the 

 nucleus is situated. Some observers speak of two nuclei in 

 a single cell : this, however, must be an exceedingly rare 

 occurrence, as I have never yet met with a single example 

 of the kind. 



The conoidal epithelium is, as already remarked, divisible 

 into two kinds. 



Naked Conoidal Epithelium. 



Distribution. This subdivision of epithelium, to which 

 the description just given more immediately applies, is met 

 with investing the mucous membrane of the alimentary 

 canal, extending from the cardiac extremity of the stomach 

 to within two or three inches of the rectum ; it is encoun- 

 tered likewise lining the several ducts and prolongations 

 which communicate with this : thus this form of epithelium 

 exists in the gall-bladder, where it is of a deep yellow colour, 

 in the ductus communis choledocus, in the pancreatic duct, 

 and in the mucous crypts or follicles imbedded in the 

 mucous membrane. It is found also in the upper portion of 

 the nares, in the salivary ducts, in the appendix vermiformis, 

 and in a modified form in the vas deferens. 



In the stomach, the naked conoidal epithelium does not 

 exist in an unmixed form ; it occurs intermixed with pave- 

 ment epithelial cells, probably derived from the oesophagus, 

 and carried down during deglutition. 



It is in the gall-bladder, the small intestines and the ap- 

 pendix vermiformis, that the naked conoidal epithelium exists 

 in the greatest perfection. 



