ON THE ANATOMY OF ECHINOCOCCUS VETERINORUM 203 



nococci from the granular contents of the secondary cysts described 

 by Von Siebold (vide infra). 



The mennbrane of these cysts was traversed by a meshwork of fine 

 clear delicate vessels, with distinct walls and about To^()o-tl^ to to Jinrth 

 of an inch in diameter. These were not folds, as their lumen could be 

 clearly seen at the edge of a cyst (fig. 8). They terminated in a some- 

 what wide space at the base of the pedicle of each contained Echino- 

 cocciis, and in one instance I traced a vessel for some distance into 

 this pedicle. There were no cilia nor granules contained in these 

 vessels, but they precisely resemble those canals of which traces were 

 seen in the Endocyst, and their development will, I think, show that 

 they are identical with them. 



I may anticipate so far as to say that I believe that these vessels 

 represent the water vascular system of the parent-cyst. 



A dark spot may be observed upon the surface of fig. 9. This 

 was a blunt yellowish wrinkled process, like that represented in the 

 lower portion of fig. 7. It was the onlj' projection of the kind in this 

 specimen. 



When such a sac as this is burst the Echinococci become everted, 

 and the secondary cyst turns itself inside out, so that the Echi- 

 nococci appear to be seated like Polypes upon a central stem. 

 This curious peculiarity has led to much misconception as to the 

 mode of their attachment zvithin the cyst. Von Siebold, however, 

 pointed out the true nature of this process as far back as 1837 ^ 

 (vide infra). 



The smallest free secondary cysts varied in size, as I have said, 

 down to li-jjth of an inch, when they contained only four Echinococci, 

 (PI. XXIX. [Plate 22] fig. 6.) These, however, were quite as large 

 as those in the largest secondary cysts. 



The structure of the middle-sized and small vesicles was in most 

 respects the same as that of the large ones, but there was this differ- 

 ence, that they possessed, attached to their outer surface, by pedicles, 

 a variable number of oval bodies of the same average size as the 

 Echinococci or less, but presenting a yellow wrinkled appearance, 

 containing very few corpuscles, often none, and either exhibiting no 

 trace of the circlet of hooks (fig. 6) or offering only a few, dark irre- 

 gular and withered looking ones (fig. 7). It was impossible to con- 

 found these external bodies with accidentally everted internal heads, 

 three of which are represented at the upper part of fig. 7 ; the appear- 



1 The Echinococci ^te figured in this everted state by Chemnitz (quoted by Siebold, art. 

 Parasiten, Wagner's Encyclopcedia, &c.), by Erasmus Wilson (Medico-CIiir. Transactions, 

 184S), a"'! by 2"^''' (Microscopical Transactions, 1846), 



