THE UDDER. 



length of about 12 to '20 millimetre ('0047 to '0078 inch) and a breadth 

 of -09 toll millimetre ('0035 to '0043 inch). According to Heidenhain, 

 the delicate tissue which sur- 

 rounds the alveoli consists of a 

 structureless membrane, the so- 

 called tunica propria, to the 

 inside of which is attached cel- 

 lular tissue. The internal surface 

 of this net-work of cells is further 

 lined with a continuous single 

 layer - of epithelial cells (fig. 6). 

 The diameter of these cells, on an 



average, is about '04 millimetre, and their form shows extraordinary 

 variations, according as the cow is in milk or not. In the latter case 



Fig. 7. Capillaries of Mammary Glands, 

 (x 180.) (Fiirstenberg.) 



-o 



Fig. 8. Milk -cis- 

 tern and Outlet Tube 

 of Milk -gland, laid 

 open. Two thirds of 

 natural size. 



a, Basis of teat; b, 

 upper end of milk- 

 cistern ; d, loAver 

 end of same and 

 upper end of teat ; 

 e', dilatation of 

 canal of the teat; 

 /, rosette on end 

 of lower portion 

 of canal of teat; 

 h, small, and o, 

 large gland-ducts. 

 (Fiirstenberg.) 



the epithelial cells are low and flat, while in the former they are swollen 

 and protrude comparatively far into the alveolian cavity. On the 

 outside, the membrane of the gland-lobules is surrounded by a highly 



