596 DEVELOPMENT OF THE ECHINOCOCCUS-BLADDER. 



from the contents. It was then seen that the latter consisted, like 

 the yolk, of a clear granular matrix, which contained numerous fatty, 

 shining, coarser granules. The distribution of the latter was some- 

 what irregular, inasmuch as they were more numerous in the periphery 

 than in the interior. For the same reason, the central contents 

 appeared clearer than the peripheral ones, but this was the only point 

 in which they differed. The contents of the zona were thus still 

 perfectly solid, for no formation of fluid had yet set in. 



The cells, which lay above the young Echinococcus, formed a thick 

 envelope, whose separate elements were so indistinctly defined that at 

 first sight it looked like a continuous granular substance. The size of 

 these cells was somewhat large, on an average about 0*027 mm. Each 

 of them contained a clear vesicular nucleus, from 0*007 mm. to 0*012 

 mm. in size, in which there were usually embedded two or three dis- 

 tinctly defined nucleoli. Sometimes I found cells with an oval or 

 elongated nucleus, or even with two nuclei, which were at a variable 

 distance from one or other. In the latter case the cellular mass was 

 usually constricted between the nuclei. There is thus no doubt that 

 the cells of this enveloping layer undergo active division, in exactly 

 the same way as I have observed in other bladder- worms, and especially 

 in those of the liver. 



As to the connective-tissue cyst which enclosed the Echinococcus 

 and the enveloping substance, it was only of insignificant thickness, 

 and was everywhere in direct continuity 1 with the connective-tissue 

 trabecular network of the liver. We can hardly be wrong in sup- 

 posing that it originates principally from the latter by local develop- 

 ment and proliferation. In all cases, moreover, it was the interlobular 

 tissue that contained the parasites. The number of these amounted 

 to from four to six dozen, but none were found in any other situation. 



If, however, any uncertainty had existed regarding the nature of the 

 bladder we have described, the case of the second pig, which was killed 

 four weeks later i.e., eight weeks after the feeding would have most 

 certainly removed it. The liver of this one was most certainly studded 

 with Echinococci, but they had in the meantime grown on an average 

 to double the size of the previous ones. Even with the naked eye 

 this increased size could be perceived, for the young Echinococci shone 

 through the enveloping walls like clear drops. 



The cysts had of course also grown in proportion to, although 

 much less than, the parasites. Only in a few did the diameter exceed 

 1*5 mm., and that always in those whose inmates had also attained 



1 According to Naunyn, a distinct connection can be proved between these cysts and 

 the wall of a vessel. " It thus appears," remarks this author, " as though the embryos of 

 Tcenia ecfiinococcus were distributed through the vascular system." 



