IO2 



tubes or tracheae). Note that these branch and 

 ramify upon the surface of the mid-gut and malpighian 

 tubes (Fig. 39). 



2. Large muscular fibres, together with elastic 

 fibres, forming a meshwork. Note that they are 

 circular and longitudinal (external). Note that at 

 the edge of the viscus they are seen in optical section 



(Fig- 39)- 



3. Large cells with large nuclei and granular 



protoplasm (epithelium of mid-gut). Note some in 



Fig. 39. Microscopic appearance of Mid-gut, shewing Cell 

 Structure and Zygotes 



situ forming a single layer of polygonal epithelium? 

 and others detached and in process of being carried 

 along by fluid streaming from interior of mid-gut. 

 Note that in some places these cells are undergoing 

 vacuolisation with dancing of the protoplasm granules 



(Fig- 39)- 



