Note 725 — LETTER XII.
Reading edition
The mode, however, in which this is effected in all insects furnished with a proboscis, can scarcely be by suction, strictly so called, or the abstraction of air, since the air-vessels of insects do not communicate with their mouths: it is more probably performed in part by capillary attraction; and, as Lamarck has suggested, (Syst. des Anim. sans Vertèbres, p. 193.) in part by a succession of undulations and contractions of the sides of the organ.