586 DEFINITION OF T^NIA ECIIINOCOCCUS. 



multiple Echinococci in the liver and other viscera, all the cysts which 

 lay under the peritoneal coating of the intestine, and were connected 

 with it only by a more or less long, thin stalk, were devoid of daughter- 

 bladders and heads (or had only very small ones), while all the others 

 exhibited the normal structure. 



The rarity of the heads is also the reason why the true nature of 

 the so-called " multilocular " Echinococcus was misunderstood, until 

 Virchow's researches. * The small component bladders used to be con- 

 sidered as colloid masses, and the whole as an alveolar colloid cancer. 



Taenia echinococcus, von Siebold. 



Von Siebold, "Ueber die Verwandlung der Echinococcusbrut in Tanien," Zeitscltr.f. 

 wiss. Zool., Bd. iv., p. 409, 1853. 



A tape-worm of comparatively small size, and with only three or 

 four joints, of which the last, when mature, exceeds all the rest of the 

 body in size. The total length is only a few (at most 5) millimetres. 

 The small hooks have stout root-processes, and are seated on a somewhat 

 swollen rostellum. Tlieir number usually amounts to some thirty or 

 forty. 



The young stage, long known under the name Echinococcus, forms 

 very conspicuous, almost motionless bladder, with a thick, elastic, 

 and frequently laminated wall, on whose inner surface, in special 

 brood-capsules of the size of a millet-seed, there are budded off 

 numerous small heads, almost invisible to the naked eye. Not un- 

 frequently the bladder increases by budding either externally or in- 

 ternally; it may thus become a composite system of larger and 

 smaller bladders, one within the other. Such bladders are found 

 especially in man and the ox, while other ruminants swine and 

 monkeys usually harbour either simple bladders, or those with 

 exogenous multiplication. 2 The favourite place for the Echinococcus 

 is the liver or lungs ; but there is hardly an organ which may not 

 harbour it. The adult tape-worm lives socially in the intestine of 

 the dog, jackal (Panceri), and wolf (Cobbold). 



Description of the Adult Tape- Worm. 



The head of Tcenia echinococcus is characterised not merely by its 

 small size (its transverse diameter is scarcely 0'3 mm.), but also by 



1 Verhandl. d. med. phys. Gesettsch. z. Wiirzburg, Bd. vi., p. 84, 1855. 



2 With the exception of the peacock, in which an Echinococcus was detected by v. 

 Siebold, and lately again by Pagenstecher, mammals are the only hosts of this worm. I 

 may here mention as well the occurrence of an Echinococcus in the liver of a squirrel, 

 which I found noted in one of my uncle F. S. Leuckart's papers. 







