THE LARVA OF SARCOPHAGA. 1 67 



into that of the stigma very minute slender processes arise from 

 it into the lumen: these processes branch and rebranch to form 

 a reticulated layer which takes the place of the taenidia of the 

 trachea (Fig. 10, r.). This reticulated layer is increased until the 

 entire lumen is rilled with a reticulated mass or plug (Figs. 8, 

 7 md 9, rp.). At the base of each papilla the reticulated plug 

 branches and continues to near the tip of the papilla where there 

 is a -mall chamber into which the branch of the reticulated plug 

 sends its terminal filaments (text-figure i). Thus we find 



KrP! 



i Lou il section of a papilla of the anterior atigma, showing the termi- 



n.il i li.iiiil>i-i mi< which filaments of the reticulated phi. t. X 1.500. 



the entitle, trachea! lining and the cuticular mas- of the -ti-ma 

 lo he t\\o-l,i\ercd. In all three places the non-staining I i\er is 

 little iiin.lilied ; but in the tracheal lining the deeply staining layer 

 i- iiiinliiied to form the taenidia, and in the tracheal pmce-- it 

 I" ..... i - .1 reticulated plug. 



The lar\.e of blow-lly and house fly have likc\\i-e pn 'thoracic 

 siigniatir processes with finger-like papilla-. The-e in turn, 

 a. onlini; to de Meijere ('02), have reticulated plni;- which he 

 rail- "felt -chambers" (Feltkammern). What does -uch histo- 

 lo-ji-.il -tructure mean? We see the cuticular hair- mianlin- the 

 >tumata ot ants or other insects and we interpret them as being 

 <le\i< . ^ to protect the trachea from foreign bodie-. lint hen- \ve 

 ha\c in ]lace of protecting hairs an exten-i\e. Imelv reiiculated 

 phi:; \\hich resembles the cotton plug ot a bacterial culture tube 

 .1- though it were constructed for the purpose of protecting the 

 trachea from microscopically minute bodies. Tin- lar\a feeds 

 upon the suppurated fluid found within the excavated region 

 of the nucha of the host, hence while the larva is feeding these 

 bacteria can hardlv be of service, for the anterior end of its body 



