548 Hans Przibram asserts that the linear ratio of successive chambers tends in many Foraminifera to apôÙproxôÙiôÙmate to 1ôñ26, which =ã₤ãÿ£¢2; in other words, that the volumes of successive chambers tend to double. This Przibram would bring into relation with another law, viz. that insects and other arthropods tend to moult, or to metamorphose, just when they double their weights, or increase their linear dimensions in the ratio of 1ã₤:ã₤ãÿ£¢2. (Die Kammerprogression der Foraminiferen als Parallele zur HûÊutungsprogression der Mantiden, Arch. f. Entw. Mech. XXXIV p. 680, 1813.) Neither rule seems to me to be well grounded.
551 Brady, op. cit., p. 206; Batsch, one of the earliest writers on Foraminifera, had already noticed that this whole series of ear-shaped and crozier-shaped shells was filled in by gradational forms; Conchylien des Seesandes, 1791, p. 4, pl. VI, fig. 15aãf. See also, in particular, Dreyer, Peneroplis; eine Studie zur biologischen Morphologie und zur Speciesfrage, Leipzig, 1898; also Eimer und Fickert, Artbildung und Verwandschaft bei den Foraminiferen, Tû¥binger zool. Arbeiten, III, p. 35, 1899.
552 Doflein, Protozoenkunde, 1911, p. 263; ãWas diese Art veranlûÊsst in dieser Weise gelegentlich zu varû¥ren, ist vorlûÊufig noch ganz rûÊthselhaft.ã