Page:The Zoologist, 4th series, vol 1 (1897).djvu/290

262 purpose of deciding this question, I believe I had the good fortune to be the first to observe and record the actual process. If the different books which have been written on the subject of Annelids be examined, it will be found that they either pass over this question in silence, or give a very vague and unsatisfactory account of the process. Some time ago, however, a pleasant surprise was granted me. I was trimming up my flower-beds ready for Christmas. The soil was inhabited by a large number of Earthworms of various species. When I first began the study of these creatures only about ten British species were known. I have now raised the number to a quarter of a hundred. As I was examining the different species on the day in question, I presently detected a happy pair in the very act of manufacturing their cocoon. It was the first time in all my experience as a naturalist that such a treat had fallen to my lot, but I have since repeated the observation more than once on other species of Annelids. The process is as follows:—

When two worms are about to form an egg-case it is necessary that they should work in unison. One worm cannot do the work alone, though each worm is at the same time both male and female or hermaphrodite. A pair therefore approach each other from opposite directions, each having its head towards the other's tail. Near the middle of each adult worm is a swollen portion called the girdle or clitellum. This peculiar organ yields the horny substance of which the egg-case is formed, but it is at first soft and pliable, hardening after exposure to the air and cold. When the worms are ready for the process of oviposition the chitine is formed into a girdle around their two bodies, so that for the time being they are tied together. When the case is complete the necessary contents are poured into it from the two animals, after which they withdraw from each other backwards, and so allow the capsule or egg-case and its precious freight to slip over their heads and fall to the ground; the ends are then drawn together, and the cocoon left to its fate.