VliTERI.NARV PATJICKJCY. 



a. ,\dult male. 



b. Adult leiiial 



-Asrarih Mjstax, alter Niles. 



a. t\i>halic extremity, 

 d Caudal. 



Extension of Disease. — Bv exten.sion of disease is meant the 

 invasion and aii'ection of adjacent strnctures and even remote 

 tissues of the body. Some diseases are necessarily local, i. e., 

 the cause is not capable of being transferred to adjacent or re- 

 mote structures, e. g., ocular filariosis. Other diseases are in 

 their earlier stages local, but later the cause may be transferred 

 to some other part and produce secondary diseased foci or 



Fig. 4y. — I>istoma 

 Hepatirum. 



a. Intt stines. 



b. Oral sucker. 



c. \'entral sucker. 



d. i'terus. 



metastases, e. g., tuberculosis. The extension of disease may 

 be produced as follows: 



First, by the cause of the disease passing along the natural 

 channels and establishing secondary diseased foci, thus, Bray 

 reports that calves become afifected with necrotic gastritis and 



