OEIGIN OF THE HEADS IN BROOD-CAPSULES. 



605 



a caudal bladder, and that not only because it forms an integral 

 portion of the head, and is included in the body of the future tape- 

 worm, but more especially because of its entirely different origin. 



Before proceeding to the discussion of these conditions I must 

 remind the reader that the earlier helminthologists believed the 

 heads to be placed directly upon the inner wall of the Echinococcus- 

 bladder. It was thought that they budded forth from this wall one 

 after another, and remained attached to it for some time after they 

 had completed their development. Even after the important dis- 

 covery of v. Siebold, that these heads were enclosed in small special 

 capsules situated upon the JZchinococcus-vf&ll, most zoologists remained 

 to some extent at least true to their former opinion, inasmuch as they 

 maintained that heads were formed and developed in two different 

 ways. Von Siebold, for example, taught that some only of the heads 

 originated in the interior of these capsules, and that others budded 

 forth freely from the wall in the form of little processes, which, from 

 the very first, were quite solid. 



But further, it was even maintained, and indeed with the concur- 

 rence of all investigators, that the connection of the head with the 

 tissue whence it sprang was only 

 temporary. It was thought that after 

 their development (and eventually by 

 the rupture of the brood-capsules) 

 the heads detached themselves from 

 their origin, and, without losing their 

 vital powers, roamed about freely for 

 a long time in the fluid contained in 

 the bladder. 



Unfortunately I am obliged to con- 

 tradict most of these assertions. 



Not only do the JZchinococcus-'hesids originate, without exception, 

 within the brood-capsules, discovered by v. Siebold, but also in 

 their normal state these brood- capsules never rupture, nor allow the 

 contained heads to escape. According to my observations, all parts 

 of the Echinococcus (mother-bladder, brood-capsule, and head) are 

 throughout life in direct continuity with each other, as indeed I have 

 mentioned above. 



I do not deny that one may often observe burst brood-capsules and 

 isolated heads, but I have only observed these conditions in encysted 

 worms, which were investigated some time after the death of their 

 host. If the worms were fresh, I found, without exception, the condi- 

 tions I have described : the heads all within their brood-capsules, and 

 all of these attached to the inner wall by means of a small stalk. 



FIG. 324. Brood-capsule, with heads 

 of Echinococous in the interior. (x40.) 



