IIH 



There are two series of spaces seen in sections 

 tlirougli the gland — the himen or gland cavity lined by 

 epithelium with all its diverticula, and the blood spaces 

 bounded by the connective tissue in which they lie 

 (figs. 42 and 43, Ren. v.) and containing scattered 

 corpuscles, so that the blood is only separated from the 

 glandular epithelium by a thin layer of connective tissue. 



The glandular epithelium is composed of cells which 

 are about three times as tall as their width. The cells do 

 not contain much stainable protoplasmic contents, and 

 high magnification shows that they are much vacuolated 

 with the protoplasm situated near to the cell bases, 

 towards which end the nucleus is also to be found. The 

 large vacuole occupying most of the cells is filled by a 

 refractive colourless or slightly brown crystalline body, 

 which is a concretion of excrete matter. The free 

 surfaces of the cells facing the lumen of the gland bear 

 delicate processes almost exactly like cilia, so that in 

 some places it is very difficult to detect any ditierence. 

 They are irregular in distribution, sometimes quite 

 abundant, and have also a beaded appearance which makes 

 them a little unlike cilia — which, moreover, have not 

 been found on the cells of the renal organ of Lamelli- 

 branchs. It is unusual for excretory cells (loaded with 

 excrete matter in many cases) to have cilia, and T am 

 inclined to think, therefore, that this very cilia-like 

 appearance is due to an excretion which takes place in a 

 fibrous manner. There are generally present in the 

 lumen of the organ masses which look as if they contained 

 these cilia-like processes. In the figure (fig. 52) these 

 are too much like cilia, and are rather too regularly 

 disposed. In addition to these processes there are always 

 to be found cells in the act of extrusion, so that by actual 

 dehiscence of the cells the excretion is thrown into the 



