ECHINOCOCCUS MULTILOCULAEIS AND COLLOID CANCER. 625 



that the earlier observers never thought of doubting their pseudo- 

 plastic nature. And they must have been confirmed in this erroneous 

 opinion by the circumstance that the multilocular Echinococcus has 

 a peculiar tendency to central ulceration (originating at first in the 

 stroma), which generally causes the death of the host. Even the 

 observation of Zeller,^ that the gelatinous bladders of the alveoli oc- 

 casionally contained a brood of Uc}dnococcus-hea.ds, did not avail to 

 alter the prevailing opinion regarding the so-called " alveolar colloid " 

 of the liver. The presence of these animals was regarded as an acci- 

 dectal complication, and the pseudo-plastic nature of the growth was 

 never doubted until Virchow ultimately established the complete cor- 

 respondence of the so-called " colloid masses " with small Echinococcus- 

 bladders.^ 



Virchow's discovery removed all doubt on this point. The only 

 question was whether or not the individual ^cAmococcws-bladders of 

 the tumours originated independently of each other ; in other words 

 whether they owed their origin to an extensive, perhaps often repeated, 

 immigration of Echinococcus embryos, or were produced by continuous 

 budding from one, or perhaps a few mother -bladders. The latter view 

 seemed the more probable, and all the more since the early observers 

 had frequently noted the irregular form and numerous club-shaped 

 processes of the colloid J^cAiMococats-bladders. 



Virchow was therefore entirely in the right when he sought to 

 explain the form of the multilocular Echinococctcs by the supposition 

 of a repeated external proliferation. It is more doubtful whether he 

 was equally right in supposing this peculiar form to be due to the fact 

 that the multilocular Echinococcus had taken up its abode in the 

 lymphatic vessels. At present, perhaps as much can be urged against 

 this conjecture as can be adduced in favour of it. Even if we suppose 

 that the root-like processes of the tumour (frequently observed, and 

 especially in Virchow's case) follow the course of the lymphatic 

 vessels, the primary position of the Echinococcus would be by no means 

 determined, since it is quite well known that the growing Echinococcus 

 not unfrequently seeks out the most diverse paths, and penetrates 

 with special preference into adjoining cavities, that is to say, into the 

 blood-vessels, and in the liver also into the gall-ducts. Indeed, we 

 have gradually become convinced that the multilocular Echinococcus 

 may be found on different occasions in all these cavities. 



lungs (Lebert), the pulmonary artery, and the sub-peritoneal tissue of the uterus (Scheu- 

 thauer), and even the intestinal wall itself, are mentioned as the seat of B. multilocularis, 

 but all these statements are doubtful, since there is some suspicion that they refer to 

 multiple Echinococd. 



^ " Das AlveolarcoUoid der Leber : " Tubingen, 1854. 



' Verlumdl. der Wurzburaer phys.-med. GeseUsch., Bd. vi., 1856. 



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