SEA-FISHERIES LABORATORY. 385 



described by MacMunn as being ciliated. This is highly 

 improbable, and it is more likely that we have in both 

 the ferment cells and the fat cells a striated hem 

 (Harchensaum) (sb.) similar to that already described in 

 the mid-gut epithelium. The nucleus is situated in that 

 portion of the cell farthest removed from the lumen. 



(3) Young cells (fig. 37, y. c). These are small cells 

 found between the larger cells near the periphery of the 

 tubules. These young cells stain deeply and will 

 eventually give rise to the fat cells or ferment cells. 



Physiology of the Digestive Gland. 



As pointed out by Cuenot, the digestive gland has 

 many functions, which may be summarised as Digestion, 

 Absorption, Excretion, Elimination and Regulation. 



Digestive function. According to MacMunn, 

 Frenzel and others the gland is a pancreas, and the 

 ferments produced (proteolytic and amylolytic) are poured 

 into the ducts of the gland and thence into the mid-gut. 

 The ferments are produced entirely in the ferment cells. 



The fat cells have the power of forming and storing 

 fat. 



Roaf* found that the action of the extract of the 

 digestive gland was as follows : — 



It does not digest coagulated white of egg. It 

 digests fibrin most actively in alkaline solution, but not 

 actively in acid solution. It converts starch into sugar, 

 and inverts cane sugar. It does not hydrolise olive oil, 

 but it hydrolises methyl acetate. 



Function of absorption. According to Cuenot the 



digestive gland is of great importance as an accessory 



organ for absorbing the products of digestion. The 



^Roaf, H. E. "A Contribution to the Study of the Digestive 

 Gland in Mollusca and Decapod Crustacea." Bio-Chemical Journal, 

 Vok I, Nos. 8 and 9. 





