LAWSONj ON HELIX ASPERSA AND HORTENSTS. 267 



very distinct and extensive structure, and deserves far more 

 attention than has been heretofore bestowed upon it. It 

 consists of a central duct, closed at its posterior extremity 

 (as shown by the obstruction to liquids introduced as injec- 

 tions), which is beset on its sides by two rows of long, white, 

 granular-looking follicles. These are observed, under the 

 microscope, to opeti into the central channel, and to contain 

 those oval and elliptical, epithelial-like cells, usually de- 

 scribed as the parents of zoosperms. The central vessel 

 now leaves the testis at the point of the union of the uterus 

 and vagina, and is continued as a simple duct for a distance 

 of an inch and a half, or thereabouts, when it terminates by 

 a rounded aperture in the penis. It is this portion to which 

 the term vas deferens has been applied. The penis is repre- 

 sented by a long, attenuated tube, wide, and of rather thickish 

 consistence at its base, which is perforated and communicates 

 with the generative outlet, csecal at its apex, which is ex- 

 tremely delicate, and situate deeply in the mass of viscera. 

 It communicates with the vas deferens by a small aperture, 

 distant from the basal opening about an inch and three 

 eighths, and measures, from end to end, when extended, 

 about three inches and a quarter. The blind extremity, 

 from its fancied resemblance to a whip-lash, has been termed 

 the flagelliform portion. About the junction with the vas 

 deferens there exists, attached to the penis, a strong mus- 

 cular fasciculus, which probably performs the function of 

 drawing back this organ after it has been averted in copu- 

 lation. 



The androgynous group includes the vagina, vas differens, 

 and sperm-sac, with its duct and caecum. 



The vagina is usually described as the termination of the 

 uterine portion ; but from the direct continuation which it 

 forms with the copulative vessels, and its almost rectangular 

 connexion with the uterus, it seems more correct to look upon 

 it as the dilated extremity of the former. Viewing it thus, 

 both may be said to constitute a tube, leading from the dart- 

 sac, on the one hand, to the sperm-sac, on the other, wider 

 at its proximal than at its distal end, about one inch and 

 three eighths in length, and one sixteenth of an inch in 

 diameter, following a backward course, beneath the superficial 

 viscera, toward the anterior margin of the liver, where it 

 expands abruptly into a spherical or pyriform bag — the 

 spermatheca, or sperm-sac. This vesicle, whose office appears 

 to be the storing up of the semen received during coition, 

 varies in its dimensions under different conditions. Thus, 

 immediately after union of the sexes, when distended by its 



