258 THE ANIMAL PARASITES OF MAN 



is termed Echinococcus multilocularis, s. alveolaris (alveolary 

 colloid.) 



It was originally regarded as a mere proliferation, and its animal 

 nature was first established by Zeller and R. Virchow. The para- 

 site, which varies in size from that of a fist to a child's head, 

 presents a collection of numerous cysts, measuring between 0*1 and 

 3 4 5 mm. in diameter, which are embedded in a connective tissue 

 stroma ; the cut surface has, therefore, a honeycomb appearance. 

 The cysts are surrounded by a pellucid and stratified cuticle, and 

 each according to its size encloses either solid cellular contents or 

 a space cavity lined by a parenchymatous layer ; the fluid contained 

 in such a cavity may be transparent or is rendered opaque by 

 globules of fat, gall pigment, haematoidine and fat crystals. Accord- 

 ing to a few authors all or most of these cysts intercommunicate ; 

 others state that this is the case at least as regards the cuticle. 



FIG. 181. Echinococcus multilocularis in the liver of the ox; natural size. (After 

 Ostertag.) 



The scolices are by no means found in all the cysts, and when 

 present in only a few, rarely half of the cysts contain scolices (one 

 or several) ; it is supposed that at least some of these little heads 

 are formed in brood capsules. 



One circumstance is peculiar to the multilocular echinococcus 

 of man, namely, the disintegration that sets in at certain stages ; 

 in the centre of the parasite a cavity forms that frequently becomes 

 very large and is filled with a purulent, or brownish or brownish- 

 green viscid fluid ; within this fluid one finds shreds of the wall 

 of the cavity, calcareous bodies, echinococcus cysts, also scolices 

 and booklets, as well as fat globules and crystals of haematoidine, 

 margarine and cholesterine and. concretions of lime. Such ulcera- 



