422 BIHFLE TUMOUHS. 



X.— PAKABITIO CTSTS. 



The compound cysts include the hydatid larval conditions of 

 many parasites, such as — 



yshcercus hovis — in the muscles of horned cattle. 

 „ celluloses — muscles of the pig. 



„ pisiformis — entrails of hares, &c. 



^ cucumerinus — body of dog louse. 



„ ienuicollis — liver, walls of mesentery, pleura, 



pericardium, diaphragm, &c. of sheep and 

 pigs. ^ 

 „ fasciolaris — liver of rat and mouse. 



Eccliinococcus veterinorum — large bladder-worms in liver, 



heart, lungs, &c. 

 Ccsnurus cereh-alis — in brain of herbivora, particularly sheep. 



Of these, however, the Ccenurus cerebralis and the Ecchincocci 

 are the only ones which attain any size. 



XT. — CYSTIC TUMOURS OF CYSTS. 



Are not now regarded as tumours in the strict sense of the 

 term. They are cavities containing a liquid or pultaceous mat- 

 ter, enclosed in a more or less distinct capsule, which may be a 

 new formation or a pre-existing structure, distinctly extravasated 

 with or by its own secretion. Paget divided them into simple 

 or barren, and compound or proliferous. 



The barren cysts contain a fluid-like serum, such as that 

 found in serous abscesses (capped elbow and capped hock), or 

 6ynovia-like fluid, as in the enlarged bursas (wind-galls) ; whilst 

 others contain a more highly organised fluid, as in ranula. 



These cysts, according to the same authority, have at least 

 thrae modes of origin. 1st. Some are formed by the enlarge- 

 ment and fusion of the spaces or areolte of the connective or 

 other tissues. In these spaces fluids accumulate ; the tissues 

 become rarefied, and gradually the boundaries of the spaces are 

 levelled down and walled in, till a perfect sac or cyst is formed, 

 the walls of which continue to secrete. 



2d. Some cysts are formed by dilatation and growth of natural 

 ducts or Bacculi, as are those sebaceous or epidermal cysts, 

 which, formed by hair follicles, have permanent openings. Such 



