NERVES OF MAMMAE. 551 



In the nipple the excretory ducts are surrounded by a tissue ana- 

 logous to the dartos of the scrotum, to which the power of erectility 

 of the nipple seems due. There is no appearance of any structure 

 resembling erectile tissue. 



Vessels and Nerves. The mammae are supplied with arteries 

 from the thoracic branches of the axillary, from the intercostals, 

 and from the internal mammary. 



The Lymphatics follow the border of the pectoralis major to the 

 axillary glands. 



The Nerves are derived from the thoracic and intercostals. 



