GENERATIVE JiYSTEM. 307 



them to the albugiueous tunics of the testicles. Internally, the 

 ovaries are composed of a whitish spongy substance, in which 

 are, in some instances, found little vesicles containing a yellowish 

 glairy fluid, in others one or more dark yellow or brownish sub- 

 stances, named corpora lutea: the vesicles are the ova, which 

 from impregnation take on further development ; the corpora 

 lutea denote the parts from which vesicles have already burst, 

 and consequently only exist in the ovaries of mares whose organs 

 have been engaged in the generative process. Prior to the age 

 ripe for sexual intercourse these bodies are small and white ; but 

 as soon as the time for copulation arrives, they grow large, redden 

 externally, and present many yellow spots or streaks through 

 their substance within. 



Organizatiou. — The arteries supplying all these parts are — 

 1. The vaginal artery, a branch from the internal iliac, which 

 accompanies the obturator artery, and afterwards dips down by 

 the side of the vagina, upon which it branches out in various 

 directions, sending some ramifications in its way to the rectum, 

 and transmitting others to the uterus and bladder. 2. The 

 uterine artery, a branch from the external iliac, coming otT after 

 the ilio-lumbar, and distributing its branches principally upon 

 the cornu uteri. 3. The spermatic artery, coming from the aorta, 

 is convoluted in its course, and supplies the ovary, fimbriated 

 body, and Fallopian tube. 



The nerves are derived from the hypogastric plexus. Both 

 the vessels and nerves take their passage between the layers of 

 the broad ligaments, insinuate themselves underneath the peri- 

 toneal covering, obliquely pierce the substance of the muscular 

 tunic, and ramify extensively between it and the internal mem- 

 brane. 



APPENDIX 



TO THE GENERATIVE ORGANS. 



THE UDDERS. 



Although not immediately concerned in the process of genera- 

 tion, these organs co-operate towards the same important end — 

 the continuation of the species. 



The mamm^, or udders, are two flattened oval-shaped bodies, 

 formed for the purpose of secreting milk. 



Situation. — They depend between the thighs from the postero- 

 inferior part of the belly, in quadrupeds in general ; but in the 

 human species, and in the ape tribe, they are attached to the 

 breast. The advantages resulting to the quadruped (who has 

 no power of erecting himself or handling his young) from this si- 



