30 the a>~ato:my of the leech. 



year, in the Earth-worm, this duct, which may be called the inferior duct of the 

 ovario-uterine organ, is crowded with living young, emerging from the ova, and in 

 process of final extrusion through the external orifice. The hatched young in the 

 Leech have never yet been seen actually by the author in this situation, although 

 the parts are accurately correspondent in the two worms. He cannot yet there- 

 fore state of the Leech what he can from actual observation of the Earth-worm. 

 that it is viviparous; the superior duct of each ovarian uterus passes underneath 

 the common longitudinal chord and opens into the true testicular duct, the two 

 channels becoming united into one, just before entering the substance of the gland. 

 It is desirable here to warn the anatomist, that in practice the demonstration of this 

 fact demands great patience and minuteness of dissection. 



The author now desires to solicit special attention while he attempts to explain 

 the nature of the connexion which, according to his view, subsists between the 

 male organ or testis on the one hand, and the egg-producing and egg-incubating 

 organ or ovarian uterus on the other. It will, he trusts, suffice to elucidate satis- 

 factorily the mechanism of self-impregnation. The testicular bodies secrete a true 

 sperm-fluid, the cells of which can readily be detected by the eye both in the duct 

 ■which leads to the great longitudinal chord, and in that which conducts into the 

 ovarian uterus. The male seminal fluid travels from the testes into the 

 ovarian uterus along the superior of these ducts. It may be actually detected in 

 the cavity of this latter organ, where it comes into immediate contact with the ova 

 whereby impregnation results. The ova thus fertilized travel gradually onward, 

 and reach the inferior half of the ovarian uterus. As in the Leech, these ova may 

 be discovered as ova at a point in the oviduct very near the outlet, it is probable 

 that this Ar.nelid is oviparous. This fact, which is little material, may be readily 

 determined by examination instituted at tbe right season. The curved OTario- 

 uterine membranous organ is really the part to which Duges applied the name of 

 " the cardiac vasiform heart,'' and which M. Quatrefages has denominated " la 

 poche secretrice ! ! " Duges made a near approach to a correct descriptive 

 anatomy of this organ. Quatrefages' delineations are extravagantly erroneous. To 

 each ovarian uterus a beautifully delicate vesicle is attached. It is connected with 

 the superior duct, or that which leads directly from the testis into the ovario- 

 uterine saccule by meat s of a very slender tubule rising from the vesicle. This 

 vesicle is the far-famed " respiratory sacculus" of the Leech ; the duct communi- 

 cating between it and the superior half of the ovarian uterus is the wondrous res- 

 piratory heart vessel, which for half a century has challenged the admiration of 

 anatomists ! 



Let it now be seen what rational and probable physiological explanation these 

 parts will bear. In the first place, it is obvious that there exists in this Annelid 

 a direct communication by means of an open duct between the male and female 

 elements of the reproductive system ; that this system opens externally only at the 

 orifice of the oviduct; that these orifices are designed for the extrusion of the ova 

 or young from the body of the parent, and not for the reception of the sperm-fluid 

 into the ovario-uterine tract; that the male fertilizing secretion passes directly 

 along the duct into the ovarian uterus; and that thus the process of .^/-impreg- 

 nation is ^t7era% accomplished, for it is not the sperm-fluid of another individual 

 that fecundates the ova, but that of the same individual. 



Thai conclusion may be affirmed with confidence, since the median copulative 

 saccule into which the intromittent organ of another individual is inserted termi" 



