528 THE ANIMAL PARASITES OF MAN 



takes place. The head falls off, is partly destroyed or undergoes more or less 

 change, and swims about in the fluid. The contents thicken. A considerable 

 deposit of calcium salts occurs and the shrunken sac may finally be represented 

 by a single calcified nodule. 



The echinococcus multilocularis, which in form so strongly resembles an 

 alveolar colloid of the liver that hitherto its original nature has often been 

 entirely misunderstood, must next be mentioned. It is found chiefly in the 

 liver, but also occasionally in the brain, the heart, the diaphragm, and the 

 pleural cavity ; in the psoas muscle, the lung, the gall-bladder, the kidney, and 

 the adrenals ; in the uterus and anterior wall of the chest ; in the duodenum ; 

 in the portal and peribronchial lymph-glands and in the bones. The multi- 

 locular or alveolar echinococcus is characterized by small irregularly formed 

 cysts which are separated from one another by masses of connective tissue 

 enclosing a gelatinous plug. In section we recognize a honeycomb-like struc- 

 ture. All the cysts possess the properties of echinococcus cysts except for slight 

 deviations. Upon the inner surface there are frequently layers of granular 

 fatty material or pigment, besides balls with radiating stripes which consist of 

 an organic base impregnated with calcium salts. Not rarely needle-shaped 

 or sheaf-like crystals and hematoidin crystals are also noted. Seolices are 

 often absent. 



The limits of the tumor are quite sharply circumscribed. Now and then 

 smaller isolated tumors are found adjacent. Virchow saw strands resembling 

 a pearl necklace, the parts of which projected like processes. The .capsule is 

 invariably of a cartilaginous hardness, and adherent to the surrounding tissues. 



This echinococcus was for a long time held to be only a variation in the 

 form of the cystoid echinococcus, due to its growth in the blood-vessels, lymph- 

 vessels, and biliary channels. 



Its characteristic alveolar structure, as well as the conspicuous variation ia 

 its geographic distribution, has raised doubts as to the identity of the multi- 

 locular with the hydatid forms. To decide this question, experiments in 

 feeding dogs with the echinococcus multilocularis were undertaken. Klemm, 

 Vogler, Mangold, and Miiller raised tenige which in the form of their hook- 

 lets, as well as in the position of the eggs in the terminal section, differed 

 from the tenia of the cystoid form. Mangold also succeeded, by feeding with 

 a tenia which he had raised, in developing two tumor foci in the liver of a pig; 

 these were recognized as echinococcus multilocularis. The occurrence of mul- 

 tilocular echinococcus in certain geographical regions is well known. Accord- 

 ing to Vierordt, it is found frequently in Wiirttemberg, Switzerland, Bavaria, 

 also in Austria and Eussia, occasionally in Prussia, Baden and North America. 

 Eecently Posselt has called attention to a previously unknown region of dis- 

 tribution in the Tyrol ; Pichler described a case of echinococcus multilocularis 

 in Karnten. It is especially interesting to note that in the " classical coun- 

 tries " of the hydatid echinococcus, Iceland, Australia, Mecklenburg and New 

 Pomerania, Dalmatia and Argentina, the echinococcus multilocularis does not 

 occur at all or has been very rarely observed. On the other hand, in the specific 

 regions of distribution of the multilocular echinococcus, in Bavaria, Wiirt- 

 temberg, and Northern Switzerland, the hydatid form is quite rare. In conse- 



