Note 548 — Chapter XII · THE SPIRAL SHELLS OF THE FORAMINIFERA

Hans Przibram asserts that the linear ratio of successive chambers tends in many Foraminifera to ap­prox­i­mate to 1·26, which = ∛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 1 : ∛2. (Die Kammerprogression der Foraminiferen als Parallele zur Häutungsprogression der Mantiden, Arch. f. Entw. Mech. XXXIV p. 680, 1813.) Neither rule seems to me to be well grounded.