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Wisconsin Academy of Sciences , Arts and Letters . 
as, amniotic secretion; p , one of the thoracic appendages; ch, 
chorion; ecd, ectoderm; ms, mesoderm; ct, connective tissue; 
vt , yolk. 
Fig. 20. Portion of a transverse section through the ventral plate of a 
Cicada embryo before revolution, a, amnion; ecd, ectoderm; 
ap, pleuropodium forming as an apple-shaped thickening of 
the ectoderm; gl, ganglion of the first abdominal segment; 
ms, mesodermic tissue. 
