Xo. 489] SILK (iLAXDS OF M'AXTI-LL 



two tubes of the al)(h)iniiial (livi>i()ii in ilie fir>i al) 

 and extends cephaUid in ilic >!i<'rt <hict wliicli he 

 of the sub-oesophageal oanylion. 'I'lic dmracic 

 divided into three well defined parts,- the 1st, or i 

 the 2iid, or middle thoracic; and the ;ird, or y 



The 3rd, or posterior thoracic, division during 

 larval life consists of an almost straight cxlin.lri 

 it becomes nnich comolnted and it^ ^^al^ i)e<-om 

 in every way it markedly resembles the abdomin; 

 cytoplasm is denselv grainilar, deeply staining, a 

 lated, especially near the {)eri))liery of the cells (PI. 

 16). 



The 2ml, or middle thoracic dixi.ion. is 'piite si- 

 lt extends from the beginning of the second tho" 

 the first division. The cells of tliis portioii of tl 

 greater radial diameter than in any other parr 

 "gres" or '*gum," so prominent in the Ist di\is 

 and in some places difficult to distinunish. The ct 

 ized by a faintly staining, loosely granular cytoph 

 the periphen-of the cells, is much vacnolated 

 20). 



The 1st, or anterior thoracic divisi<.n. 

 It extends from the bciiiiutiim of the lirsi ihoraci 

 duct. This portion of the uiand !> chaiactevi 

 layer of "gres" or "ixnm" adhering ( h 

 the secreting cells (IM. 1, i'vj;. -'■'); pi. 



