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"<em>A</em>, simple tubular gland; <em>B</em>, gland with mouth shut and sac formed; <em>C</em> gland with a coiled tube; <em>D</em>, plan of part of a racemose gland." &mdash; Blaisedell, 1904

Secreting glands

"A, simple tubular gland; B, gland with mouth shut and sac formed; C gland…