92 MASTITIS OF THE COW 



of primary tubercles a very large necrotic nodule may be 

 formed. 



Secondary Alterations of the Necrotic Mass. — 

 This necrotic mass, which is yellowish-white in color and 

 is firm and caseous through coagulation, can undergo cer- 

 tain changes. 



It can become swollen and softened and be transformed 

 into a pulplike mass by the imbibition of lymph, made pos- 

 sible during the lactation period by increased blood- and 

 lymph-supply to the organ. 



Under reverse conditions, that is scarcity of hmph, 

 as in the alactiferous udder, they can become dry, firm and 

 finally by resorption of liquid and infiltration of calciimi 

 salts become partially calcified. The calcification begins in 

 the centre of the necrosis and progresses toward the periph- 

 ery. Thus, through resorption of liquid and calcifica- 

 tion, the area of necrosis forms a concrement which is 

 situated in the tissue of the stroma. This concrement may 

 be called a tissue concrement to distinguish it from the liquid 

 concrements which are formed in milk, ui'ine, bile and other 

 fluids. 



In the softening of an area of necrosis during a reverse 

 process, sandlike granules or sediment may form in the 

 pulplike necrotic mass, due to infiltration of lime. 



Disturbance of Circulation by Tubercles. — Since 

 tubercles are situated in the lymph-spaces of the connective 

 tissue, they finally obstruct the circulation of lymph if they 

 occur in great numbers. The lymph stagnates in the 

 lymph-vessels in the most posterior portions of the hind 

 quarters of the udder. In this manner oedema is produced 

 in the quarter affected, likewise in the entire half of the 

 udder, following tuberculosis of the supramammary lymph- 

 glands. In this condition these glands and finally the 

 lumbar-glands become oedematous. 



