46 



Anatomy of the Rabbit. 



(8) The urinogenital system, comprising the reproductive 

 and excretory organs, together with their common ducts — the 

 urethra of the male and the vestibulum of the female — and the 

 associated bulbourethral gland. The reproductive organs com- 

 prise, in the male, the central organs or testes, and the deferent 

 ducts, both of which are paired, the unpaired seminal vesicle, 

 and the paired prostatic and paraprostatic glands. In the 

 female, the reproductive organs comprise the paired OVaries, 

 uterine tubes and uteri, together with the unpaired vagina. 

 The excretory organs of both sexes comprise the paired kidneys 



and ureters and the unpaired 

 uriniary bladder. 



Certain organs of the body 

 are not included in this classifi- 

 cation: (i) The thymus and 

 thyreoid glands are connected 

 with the digestive tube in che 

 embryonic condition, and for 

 this reason are sometimes in- 

 cluded with the digestive system, 

 although in the adult they occur 

 as independent structures. (2) 

 The suprarenal body is situa- 

 ted close to the kidney of either 

 side, but is independent of the 

 latter, both in the adult condi- 

 tion and in point of develop- 

 ment. (3) The special (olfac- 

 tory, optic and auditory) sense- 

 organs of the head are highly elaborated structures, the relations 

 of which are partly with the central nervous system. 



Fig. 22. Rabbit-embryo of loi days (4.8 

 mm.) : m., mandibular; h., hyoid; i and 2, fiist 

 and second branchial arches; a.l., anterior 

 limb-bud; me., metameres; p.l., posterior 

 limb-bud. (After Minot and -Taylor, in 

 Keibels Normentafeln, v.; Fig. 12.) 



GENERAL ORGANIZATION. 



In the rabbit, as in all vertebrates, the general plan of organiza- 

 tion involves three chief features, as follows: 



(i) Axial orientation. The axial line of the body is indicated 

 by the chief portion of the skeleton, and the important organ- 



