Robert Brown, On the organs and manner of fecundation in orchideae and asclepiadeae. London, 1833. "a single circular areola, generally somewhat more opake than the membrane of the cell . . . only one areola belongs to each cell. . . . This areola, or nucleus of the cell as perhaps it might be termed, is not confined to the epidermis, being also found not only in the pubescence of the surface particularly when jointed, as in Cypripedium, but in many cases in the parenchyma or internal cells of...

Robert Brown, On the organs and manner of fecundation in orchideae and asclepiadeae. London, 1833. "a single circular areola, generally somewhat more opake than the membrane of the cell . . . only one areola belongs to each cell. . . . This areola, or nucleus of the...