MT7LTILOCULAR HYDATIDS. 701 



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CHAPTER XI. 



MTJLTILOCULARHYDATIDS. 



ETIOLOGY. Recently, on post-mortem examination, large portions 

 of the liver have been found transformed into a peculiar mass, which 

 consisted of a connective-tissue stroma, and numerous large and small 

 cells filled with a gelatinous substance. The first observers considered 

 these growths as alveolar carcinoma ; but careful microscopical exam- 

 ination showed that the gelatinous contents of the cells consisted of 

 the tissue peculiar to the echinococcus, and hence placed it beyond 

 doubt that the affection was due to a brood of hydatids. 



It is difficult to determine the mode of origin of these tumors, 

 which, according to Virchow are designated multilocular echinococcous 

 tumors ; but it is most probable that this is not a peculiar species of 

 parasite, but only that there is a peculiarity about the migration, 

 seat, and growth. Virchow believes that this form of the disease 

 results from the echinococcus embryo entering the lymphatics of the 

 liver, and their sacs developing there: LeuJcart locates these pro- 

 cesses in the blood-vessels ; Friedreich, who, in one case found the 

 hepatic duct plugged with echinococci, locates them in the gall-ducts. 

 I am indebted to a letter from JSfachenmeister for the following simple 

 explanation, which I believe to be the correct one : " After the emi- 

 gration of an echinococcus embryo, instead of the usual form of the dis- 

 ease, we have a multilocular hydatid cyst, if no connective-tissue sac 

 form around the embryo, or if this sac be ruptured by the parasite 

 before it has become hard and resisting. When the echinococcus has 

 uo firm envelope, it can grow freely in all directions, and spreads par- 

 ticularly in the directions where it finds least resistance. If in its 

 wanderings it has entered one of the many channels that traverse the 

 liver, or if it has subsequently broken through the wall of one of these 

 canals, it advances along it, and may finally fill the entire canal sys- 

 tem thus affected. As Virchow, LeuJcart^ and Friedreich, who are 

 certainly trustworthy observers, reached different results, as each of 

 these observers found different canal systems of the liver filled with 

 echinococci, we are justified in supposing that the emigrations and 

 perforation of the parasites may occur into the lymphatic, or blood- 

 vessels, or into the bile-ducts, but that each of these canal systems may 

 remain free from them. 



ANATOMICAL APPEARANCES. Multilocular hydatids almost always 

 occur in the right lobe of the liver ; in only one of the three cases thai 

 I have seen was the left lobe affected. They may reach the size of n 



