PLATE 3 



EXPLANATION OF FIGURES 



17 Cross-section of tlie wall of the larval fore-gut to show the strucduc of the 

 epithelium and muscles. The following series of photographs are all taken at 

 about the same point to show the series of changes in the epithelium and muscles 

 during metamorphosis. 



18 Cross-section of intestinal wall of a prepupa showing the eai-liest changes 

 in the epithelium and muscles. 



19 Cross-section from the same region as figure 18 from a prepupa in which the 

 intima has been cast off. 



20 Cross-section of the intestine of a young i)upa. The nuclei of the muscles 

 are now much more prominent and the pupal epithelium has secreted a new intima. 



21 From a i)ui)a about twenty-four hours old. Note the degeneration of the 

 muscles, only a densely staining mass of fibrillae remaining. The epithelium has 

 become much enlarged and vacuolate. 



22 From a pupa ninety-six hours after pupation. The ])npal intima has just 

 been shed; x, degenerating nuclei. Note the embryonic appearance of the muscle 

 nuclei. The histolysis of the muscles is now complete and wo have the beginnings 

 of histogenesis. 



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