624 



VARIOUS FORMS OF ECHINOCOCCUS. 



grow as large as or even larger than a child's head, which is, how- 

 ever, more frequently true of the Echinococcus hydatidosus than of 

 the other. 



A third form of Echinococcus (E. multilocularis) differs from these 

 principally (apart from the first stages of development, which have 

 not yet been observed) in being composed not of a simple bladder, 

 but of a group of small, even very small, bladders, which lie in 

 considerable numbers near each other embedded in a common 

 soft stroma. 



We find this Echinococcus multilocularis almost exclusively in man, 1 

 and indeed with few exceptions in the liver, 8 in which, along with 

 the stroma, it forms a usually somewhat round, firm body, about the 

 size of a fist or even of a child's head, and having at first sight more 

 resemblance to a neoplastic growth than to an animal parasite. 



If a section be made through the tumour, numerous small cavities 

 are found in the interior, usually of irregular form, separated from 



each other by a more or less thick connective- 

 tissue mass, and with somewhat transparent 

 gelatinous contents. In the intervening 

 mass there is seen here and there a blood- 

 vessel or a collapsed bile-duct. As far as 

 the tumour extends, the proper substance of 

 the liver has completely disappeared, so that 

 the limits of the former are distinctly defined, 

 and its extraction presents no great diffi- 

 culties. But occasionally there may be seen 

 issuing from the tumour a number of white, 

 pearly moniliform cords, and even thicker 

 off-shoots, which make their way into the 

 adjoining liver-parenchyma, and become new 

 foci of Echinococcus-ioTmsition at some dis- 

 FIG. 338. Section through tance from the tumour. 



The alveolar structure of the tumour and 

 the associated gelatinous bladders remind 

 one so forcibly of certain colloid growths, that it is easy to understand 



1 More recently, however, it has also been observed in the ox, for example by Huber 

 (Jahresber. d. naturhist. Vereins in Augsburg, 1861), Perroncito ("Degli Echinococci 

 negli animali domestici," p. 69, Torino, 1871), Harms (Jahresber. d. k. Thierarzneischulc 

 in Hannover, iv., p. 62, 1872), and Bollinger (Deutsche Zeitschr. fur Thiermcdicin, Bd. 

 ii., p. 199, 1875). In Huber's case, there were, beside the E. multilocularis, an E. hydati- 

 dosus as large as a fist, and a number of simple Echinococci (with heads) thus a collection 

 of all the forms which are known to us. 



* Among the cases with which we are acquainted (about forty) there is only one in 

 which the E. multilocularis was certainly observed outside the liver, namely, in the supra- 

 renal body (Huber, Deutsches Archiv f. Idin. Med., Bd. iv., p. 613). It is true that the 



an Echinococcus multilocularis 

 (nat. size). 



