3IO Veterinary Medicine. 



Virchow, who demonstrated their rather rare heads or scolices. 

 They have been found mostly in man, but also in cattle and pigs 

 (Bollinger, Brinsteiner, Ostertag). They are also confined to 

 particular countries, being unknown in Iceland and Australia, 

 where the common echinococcus prevails, and frequent in Bavaria, 

 Wurtenburg, Switzerland and Brandenburg. The specimens 

 from cattle and pigs have been obtained mainly from the abba- 

 toirs of Munich and Berlin. All this seems to indicate a special 

 variety of echinococcus. 



Longevity of Cyst. With its power of indefinite encrease in 

 numbers in the cystic form, echinococcus appears to have an ex- 

 traordinary longevity without further development. In man a 

 single case has persisted for thirty-five years (Courty), and an- 

 other for forty-three years (Raynal). In the horse one has been 

 known to last for seven years (Raymond). When vital organs 

 are attacked (heart, liver, kidney, brain) the case is usually cut 

 short by interference with the normal functions. 



Form. Size. Echinococcus cysts may thus be : {a) A simple 

 acephalocyst. (5) A simple fertile cyst containing five or more 

 heads or scolices. {/) A complex cyst, with secondary vesicles, in- 

 ternal or external, some of the vesicles containing heads or scolices 

 and some with none. 



In size the echinococcus cyst varies so largely that it is difficult 

 to make a definite statement. The simple undivided cyst may be 

 of any size up to about three (exceptionally five) inches in diam- 

 eter. The compound cyst may reach to five, six or even more 

 inches. 



Lesions. These vary much with the stage of development and 

 the organ in which the parasite is encysted. The enlargement of 

 the invaded organ, the absorption of more or less of its substance, 

 the presence of the cysts, simple or with daughter cysts, each 

 with a double layer of investing membrane, the saline (NaCl.) 

 nature of the contents, the floating of detached and devitalized 

 scolices and free booklets in the liquid, and the presence, in a 

 given number of the cysts, of live heads or scolices attached to 

 the inner membrane. The enlargement of the affected organ will 

 depend on the .size and number of invading echinococci. There 

 may be a single, simple cyst, or there may be many cysts, many 

 of them with daughter cysts. With multiple invasion the ox's 



