188G.J MR. J. D. SUTTON ON ATAVISM. 



553 



poculaiis, utriculus, or uterus masculinus. Usually it is nearly half 

 an inch long, and opens by a narrow slit in the middle of the caput 

 gallinaginis. It is Uned by mucous membrane continuous with that 

 of the "urethra, and covered by stratified epithelium. Some small 

 tubular glands open on the free surface of the mucous membrane. 



This utriculus is of great interest morphologically, as it represents 

 in the male a persistent portion of the continent segment of the 

 Miillerian ducts. Weber regarded it as corresponding with the 

 uterus, but Leuckart showed that a part of it must be looked upon 

 as representing the vagina. 



My observations induce me to regard the prostate as a suppressed 

 iiterus, the fibro-muscular tissue representing the matiicial walls, the 

 follicles correspond to the utricular glands, and the utriculus is 

 identical with the cervix uteri and that portion of the vagina 

 immediately adjacent. 



The evidence in suijport of this view will now be put before the 

 reader. In order to render every detail in clear light, we must refer 

 briefly to the fundamental structures concerned in forming a func- 

 tional uterus. 



In the Lizard, in common with the majority of the Sauropsida, 

 the ova are conveyed to the exterior by two muscular tubes lined 

 with mucous membrane, known as oviducts. The eggs, when they 

 escape from the ovaries, are received by the dilated end of the 

 oviduct, known as the infundibulum, and quickly passed onwards ; 

 they receive at thecommencement of the journey a coating of albumen. 

 Pushed on by the contortions of the tube, they arrive at the third 

 or uterine portion. Here they receive a coating of calcareous matter 

 known as the shell, and are then ready for expulsion. In these 

 oviducts, with their mucous membranes and glands, we have the 

 fundamental condition of the ducts which in the human embryo 

 conspire to form the uterus with its Fallopian tubes and vagina. 



In order to clearly describe the manner in which the Fallopian 

 tubes, uterus, and vagina are formed from the Miillerian ducts of 

 opposite sides, each duct may be conceived as made up of three 

 jiarts : — 



The upper third becomes the Fallopian tube ; the funnel-shaped 

 and usually fimbriated extremity communicates with the peritoneal 

 cavity. The middle portions of the ducts fuse togetlier, and form the 

 fiuidus, body, and neck of the uterus, whilst the lower thirds of the 

 Miillerian ducts form a vagina. Such is the commonest arrange- 

 ment. 



On comparing the parts of this compound organ with the Lizard's 

 oviduct, it becomes evident that the infundibulum and albumen 

 segment in the bird represent the Mammalian Fallopian tube, the 

 second or uterine portion corresponding with the uterus and vagina 

 of Eutheria. 



On tracing the homologies closer, we find that the portion ot 

 the bird's oviduct concerned in secreting albumen corresponds with 

 that portion of the Miillerian duct which forms tlie fundus and body 

 of the uterus ; and the utricular glands, which are concerned in 



