62 CLINICAL APPLIED ANATOMY. 



blood stream and may settle in connective tissue elsewhere. 

 Possibly embryos may also reach the liver directly by penetrating 

 that part which is moulded on the anterior wall of the stomach, 

 and may also directly infect the peritoneum by entering it after 

 passing through the stomach walls. The peritoneum may be 

 infected by the direct rupture into it of a cyst of the liver or 

 other peritoneal-covered viscus. There is no evidence that the 

 parasites travel by way of the lymphatic trunks, but it is suspected 

 that they may travel along the connective tissue planes in the 

 body ; subserous areolar tissue is a favourite nidus. 



Hydatid cysts may rupture into various passages and cavities 

 in the body. If these passages or cavities are in free communica- 

 tion with the external air or the digestive tract, as occurs when 

 the cysts rupture into the bronchi or bowel, septic organisms may 

 gain access to the cyst and suppuration ensue. 



The severity of the symptoms induced by the growth of 

 hydatid cysts is influenced to a considerable degree by their 

 situation, which determines the amount of expansion possible. 

 Hydatids of the liver and spleen may attain a great size without 

 producing urgent symptoms ; in the thorax the unyielding walls 

 and retractile lungs cause dyspnoea to be a comparatively early 

 sign ; cysts impacted in the pelvis cause marked symptoms of 

 compression of bowel and bladder ; cysts in the cranial cavity 

 and spinal canal soon produce pressure symptoms, which how- 

 ever, are sometimes modified by perforation of the bony coverings. 



In the lung the smaller bronchi may freely communicate with 

 the space which is filled by the cyst, and when the latter ruptures, 

 or is torn by the insertion of an exploring needle, the lung may 

 be deluged by the contents of the cyst, with a fatal result. 



In the heart, cysts favour the connective tissue of the auriculo- 

 ventricular septum. By rupture into the cavities of the heart 

 pulmonary or systemic embolisms may occur. 



Cysts of the liver may grow from its upper surface in the form 

 of dome-shaped projections which encroach on the lung base ; 

 such cysts usually project into the right half of the chest, since 

 this is in more immediate relation with the liver. When 



