175 



The gland itself as its name implies is finger-shaped. In 

 Scyllium canicula it is comparatively long and has a short narrow 

 duct while in Raja punctata the duct is fairly long and wide so that 

 there is not much diiference in width between it and the rather short gland. 



It is supplied by a branch of the dorsal aorta which, according to 

 Howes (6), represents one of the branches of the anterior mesenteric 

 artery and consequently, with regard to its blood supply, the gland 

 resembles the vermiform appendix of higher vertebrates — a com- 

 parison instituted by that author. 



Histology. 



I have examined serial longitudinal and transverse sections of this 

 organ and in the main have made out the structure to be similar to 

 that described by Sanfelice in 1888 (9) and by Crawford in 1899 (4). 



The central lumen is often found to contain a yellowish granular 

 substance and is bounded by transitional epithelium two or three layers 

 in thickness. 



The secondary ducts opening into this are lined with columnar 

 epithelium, the cells of which contain large oval nuclei placed near 

 to their inner ends. Goblet cells are also present. Communicating 

 with these ducts are the tubules which seem to branch in all directions 

 so that some of them are cut transversely and some obliquely in trans- 

 verse sections. Connective tissue is very scarce the sections thus pre- 

 senting a mass of these tubules with many capillaries filling up the 

 interstices. The walls of the tubules consist of low cylindrical cells 

 interspersed with numerous goblet cells. 



Crawford (4) describes the epithelium as cubical but he does not 

 mention the presence of the goblet cells. 



This tubular part of the appendix is bounded on the exterior by 

 a fibro-muscular coat the inner part of which consists chiefly of smooth 

 muscle fibres arranged in a circular direction. — Some of the fibres 

 penetrate between the peripheral blind extremities of the glandular 

 tubules. The outer subperitoneal part of the coat consists chiefly of 

 fibrous connective tissue with a few muscle fibres. This region is 

 easily distinguishable from the more muscular part by the scarcity of 

 nuclei. Numerous blood vessels lie towards the inner margin of this 

 layer some of them being cut obliquely as they pass in from the exterior. 



I have also noticed the large irregular "sinuses" often full of 

 blood corpuscles, near the central lumen as described by Crawford. 



In sections through the distal end of the gland the central region 

 is entirely composed of glandular tubules — neither main nor secondary 



