Excerpt from On Intestinal Respiration in Annelids, With Considerations on the Origin and Evolution of the Vascular System in That Group If one of the smaller aquatic Oligochaeta, such as a N MS or Pristina, be placed under the microscope and observed for a few minutes under a low power, the posterior part, or even in many cases the whole length of the intestine, will be seen to manifest recurring contractions, which constrict the lumen, and passing forwards in succession from the posterior towards the anterior end, die away, perhaps about the region of the stomach, perhaps some distance before reaching this point. These contractions are of the nature of those known as peristaltic but since they always occur in a direction from behind forwards, and not from in front backwards, they may, borrowing a term from mammalian physiology, be better described as an antiperistalsis. If the intestine itself be now more minutely examined - and though the phenomenon is often visible with a low power, it is at any rate more obvious with a high one ciliary motion will probably be seen to be actively going on within the lumen of the canal. The direction Of action of the cilia is obviously, like that of the antiperistaltic contractions, from behind forwards; the anus will probably be open, and if some particles of carmine be added under the coverslip, these may be seen to be swept in, and thence upwards along the alimentary canal for some distance. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.