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haematoxylin, alcohol-hardened specimens are seen to 

 contain numerous stained granules, collected especially 

 in the outer portion of the cell. These are especially 

 abundant in the anterior portion of the mid-gut. 

 They have also, very frequently, a number of small 

 clear vacuoles (droplets), which become more frequent 

 and of larger size towards the free border of the cell. 

 The most marked feature of the cell is the clear striated 

 border which is present in all the cells of the mid-gut, 

 but absent in all other portions of the alimentary canal. 

 The striated border is best marked in the undistended 

 organ, and becomes almost invisible in the fully 

 distended state, when the cells are much flattened. 



The nucleus of these cells is large and centrally 

 situated. 



The muscular coat is very thin. It consists of 

 an open mesh-work of long muscular fibres running 

 longitudinally and circularly. 



The individual muscle fibres are very long, 

 fusiform, striated fibres. On the outer surface of the 

 mid-gut lie numerous large branched cells in which 

 the small tracheae end, and from which bundles of 

 minute structureless air tubes pass into the wall of the 

 mid-gut. These cells are frequently well shown in 

 gold chloride specimens. Similar cells occur through- 

 out the viscera in connexion with the tracheal endings. 

 The Hind-gut. Structurally the small and large 

 intestine are similar, whilst the dilatation beyond the 

 pylorus, and especially the rectum, differ from these. 



The dilatation which occurs at the origin of the 

 malpighian tubules is thin-walled and poorly supplied 

 with muscle fibres. The cells lining it are small and 

 flattened. 



The intestine is lined with a single layer of large 

 cubical cells ; external to these is a muscular coat. 



