Plate XV 



D 



I 

 I 



'^^ 



B 

 Fig. I. 



Photograph of a dissection ( x i6) showing the proboscis (A), oesophagus (B), crop duct (C), 



crop, ahiiost empty (D), proventricukis (E), and ventricuhis (F) of a hungry fly. 



D 



> 





Fig. 2. 



Photograph of a dissection showing the same structures in a fly recently fed on gelatin. 

 Note distension of the crop. 

 (From Graham-Smith, Reports to Local Government Board, No. ^o, lyio.) 



