The female apparatus is of much less mag nitude, but also presents a sufficiently com plicated structure : it is situated between the two canals leading to the accessory vesicles of the male apparatus, and is a little posterior to the penis. The external orifice, of which we have already spoken, communicates with a short canal (fig. 74 and 76, h), of a greyish colour, which leads to a sort of pouch (i). This, accord ing to some authors, is analogous to an ute rus, but in the opi nion of other natura lists is merely a copu lative vesicle for the pur pose of retaining the fecundating liquid which is there deposited by the male in the act of copulation. This sac is bent upon itself, and a duct (j) may be observed to be continued from the anterior extremity which leads to the ovaries (k): these are small whitish bodies two in number, and in close approximation to one another.
In the earthworm, the only parts that can be regarded as male organs are some sacs or vesicles varying in number from two to seven, and situated in a longitudinal series on either side of the ventral aspect of the body towards its anterior extremity. Each of these vesicles adheres to the parietes of the splanchnic cavity, by a small canal opening directly outwards by pores placed on the posterior and inferior part of the corresponding ring : there is farther a canal of communication, which is continued directly from one vesicle to another of the same lateral series ; and at the season of pulation there is found in the interior of these organs a viscid liquid abounding with seminal microscopic animalcules. The outlets of the female apparatus occupy the sixteenth segment of the body, and are continuous internally with two narrow canals directed forwards, and situated on the internal side of the above mentioned vesicles. Having reached the ries, each of these canals (fig. 77, a) divides into two branches (b), which bend inwards and terminate by a globular enlargement (c). This is seen with the assistance of the microscope to be itself formed by a continuation of the canal puckered up into numerous folds,which are enveloped in a mon membrane. To each of these enlargements are appended a pair of ries, the entire number of which is consequently eight, four on either side. The colour of these ovaries is whitish, their texture pulpy, and their interior is beset with numerous minute vesicles, which are the ova. At the period of copulation the ovaries are filled with a whitish fluid, which is pro bably the spermatic secretion, but it is not easy to comprehend how the male apparatus can introduce it into that part.* According
to Redi, the ova, after being detached from the oviduct, pass along the whole extent of the body towards the vicinity of the anus, whence they are expelled by two orifices stated to be near the termination of the alimentary canal or to open in its interior. According to Mon tegre it is the foetus and not the ovum which traverses the body to escape by the above passages, and the lumbrici according to this view are viviparous. This statement has been adopted by many authors without perhaps sufficient examination; but, according to recent observations by Duges, it would seem not to be correct, and that what have been regarded as the young of the earthworm are in fact a species of intestinal worm.
In the naffs the male organs are less nume rous than in the lumbrici, but differ very little in other respects. They consist of a single pair of vesicles opening externally by a wind ing canal, which terminates by a small fissure on the eleventh segment of the body. The ovaries are disposed in four principal masses, between which there winds a long oviduct, of which the extremity can be protruded out wardly like a penis.-t In some annelida, as the clepsina carena, the ova are developed and hatched before exclusion, so that the young are born alive; but most of the class are oviparous, and what is very remarkable, the same ovum sometimes incloses the germs of many embryos : this is the case in the earthworm, each ovum of which produces two individuals, and in the leech the ova contain severally as many as eighteen embryos. One might at first view suppose that the same circumstances obtained in the naffs; but what appears to be an ovum with multiplied germs is in reality nothing more than an aggregate of simple ova.
Reproduction.—Some annelida not only per petuate the race by the ordinary modes of gene ration, but enjoy the singular faculty of pro ducing new individuals by a transverse division of the body. A naffs or an earthworm cut in two and placed under favourable circum stances, will continue to live, and each moiety will become, in appearance at least, a perfect animal. This fact, which was first determined by Reaumur and Bonnet, has since been veri fied by M. Duges, Sangiovanni, and many other observers : the anterior portion of the animal reproduces a new tail, and the posterior portion developes a head.