The Commens Dictionary
Quote from ‘Evolutionary Love’
Habit is mere inertia, a resting on one’s oars, not a propulsion. Now it is energetic projaculation (lucky there is such a word, or this untried hand might have been put to inventing one) by which in the typical instances of Lamarckian evolution the new elements of form are first created. Habit, however, forces them to take practical shapes, compatible with the structures they affect, and, in the form of heredity and otherwise, gradually replaces the spontaneous energy that sustains them. Thus, habit plays a double part; it serves to establish the new features, and also to bring them into harmony with the general morphology and function of the animals and plants to which they belong.
From vol. 8 of the Writings: "Peirce’s parenthetical remark is probably facetious. It is pretty likely that his well-tried hand invented it. The word has no entry in the Oxford English Dictionary, nor does it in the first edition of the Century Dictionary. The CD Supplement of 1909 has an entry for the verb “projaculate” (to dart or throw forward) and mentions that it is rare; it quotes a text of 1904 in which G. Stanley Hall uses the verb."