22 SECRETING STRUCTURES. 



It renders each cell prominent and turgid, and is the cause of its 

 dark colour. 



The dilated terminal extremities of the ducts in the liver of He- 

 lix aspersa (Miiller) contain a mass of cells. If one of these cells 

 be isolated, and examined, it presents a nucleus, consisting of one 

 or more cells. Between the nucleus and the wall of the 

 containing cell, is a fluid of an amber tint, and floating in this 

 fluid are a few oil globules. This fluid differs in no respect from 

 the bile, as found in the ducts of the gland. 



If a portion of the ramified glandular organ, which opens into 

 the fundus of the stomach of Uraster rubens (Agassiz) be exa- 

 mined, its internal surface is found to be lined with cells ; between 

 the nucleus of each of which, and the wall of the cell itself, a 

 dark brown fluid is situated. The organ secretes a fluid, sup- 

 posed to be of the nature of bile. 



The dark brown ramified caeca of the same animal exhibit on 

 their internal surfaces an arrangement of nucleated cells, the 

 cavities of which contain a brown fluid. These caeca are also 

 supposed to perform, or to assist in the performance of the func- 

 tion of the liver. 



The liver of Modiola vulgaris (Fleming) contains masses of 

 spherical cells. Between the nucleus and the wall of each of 

 these cells, a light brown fluid is situated, bearing a close re- 

 semblance to the bile in the gastro-hepatic pouches. 



The nucleated cells, which are arranged around the gastro- 

 hepatic pouches of the Pecten opercularis, are irregular in shape, 

 and distended, with a fluid resembling the bile. 



The hepatic organ, which is situated in the loop of intestine of 

 Pirena prunum (Fleming), consists of a mass of nucleated cells. 

 These cells are collected in groups, in the interior of larger cells 

 or vesicles. These nucleated cells are filled with a light brown 

 bilious fluid. 



The hepatic organ, situated in the midst of the reproductive 

 apparatus, and in. the loop of the intestine of Phallusia vulgaris 

 (Forbes and Goodsir), consists of a number of vesicles, and each 

 vesicle contains a mass of nucleated cells. These cells contain 

 a dark brown bilious fluid. 



The hepatic organ, in the neighbourhood of the stomach, in 



