406 
AV. N. F. AVOODLAND. 
described as plaiio-stereoscopic. The mass o£ the gland lies 
behind the opening of the duct on the maxilla^ seventeen 
sections (each 10 fi thick), intervening between that exhibit- 
ing this opening and that sliowing the end-sac in the upper part 
of the gland. In one respect only is the part of fig. 3 (PI. 28) 
representing tlie gland obviously conventional, and that is the 
scale of magnification of tlie details showing the general 
structure of the gland mass — the cell-layers and ducts are 
A. 
End.S: 
Text-fig. 2. 
Anterior Qp 
^ D.Mx.Gl. 
--M.Mx.GI. 
Posterior 
B 
Com. 
A. Reconstructed figure of the external appearance of the gland 
viewed dorsally in a larva 12 mm. long. In b the end-sac is 
supposed to lie dragged apart from the kidney in order to show 
the postero- dorsal situation of the connection iietween the 
two. End. S. End-sac. M. Mx. Gl. Kidney portion of gland. 
B. Mx. Gl. Duct of gland. Op. Opening of duct. Com. Tubular 
connection between end-sac and kidney. ( X 100.) 
exhibited as large and few in number, whereas in actuality 
they are so small and numerous as to be undepictable in a draw- 
ing of this magnification. This excusable convention has the 
advantage of sliowing at a glance the general architecture of 
the entire organ. 
The essential structure of the gland will be best compre- 
hended by a preliminary reference to the early stages of its 
development. In the earliest stage of development found in 
