FERTILITY AND STERILITY OF ECHINOCOCCUS HYDATIDOSUS. 617 



described simple E. granulosus, not exactly by the presence of 

 daughter-bladders for these may be produced also by the latter 

 but by the presence of daughter-bladders in the interior of the mother- 

 bladder, structures which are not only found often in large numbers, 

 but which may grow to an appreciable volume, and sometimes them- 

 selves produce daughter-bladders. Further, the large size which the 

 hydatidose Echinococcus usually attains is also noteworthy ; cases are 

 known in which it weighed from 10 to 15 kilogrammes, and therefore 

 far exceeded the largest E. granulosus. 



I cannot conceal that, among the almost countless cases of E. 

 hydatidosus reported in medical literature, there are many in which 

 no mention is made of the mother-bladder, so that the bladders 

 (hydatids) lay apparently immediately in the surrounding connective- 

 tissue cyst, and were in fact to be regarded as daughter-bladders in 

 the same sense as those of E. granulosus. This silence does not, of 

 course, warrant us in inferring the actual absence of the common 

 mother-bladder not only because the descriptions often suggest that 

 the mother-bladder was attached to the enveloping connective-tissue 

 cyst, and was considered to be an integral part of the latter, but 

 also because it not unfrequently happens in the course of time that 

 the mother-bladder is destroyed by the continually increasing number 

 of daughter-bladders. Bocker and Helm recount a whole series of 

 cases in which the mother-bladder had either degenerated or been 

 torn, and here and there the membranous remains were still found in 

 the pulpy mass enveloping the daughter-bladders. 



In regard further to the co-existence of daughter-bladders and 

 heads, the above reports must be received with caution. This is 

 especially true of the oft-repeated assertion that E. hydatidosus is 

 devoid of heads an assertion which was explained by Davaine, who 

 supposed that the formation of the daughter-bladders preceded by some 

 time the formation of heads. 1 The commonly asserted absence of 

 heads shows only that the observers failed to find them. And this 

 may all the more readily occur, since the daughter-bladders of the 

 hydatidose Echinococcus are, in point of fact, often sterile. I had to 

 examine many daughter-bladders before I found those with brood- 

 capsules and heads. Other investigators, such as Lebert and Helm, 

 have had a similar experience. On the other hand, there are 

 hydatidose Echinococci whose bladders all bear heads. Thus Eschricht 

 reports that in one of his cases all the daughter-bladders, some thirty 

 in number, both large and small, from the size of a hen's egg to that 

 of a pea, contained brood-capsules and heads. Helm similarly reports 



1 "Rech. sur les hydatides, les 6chinococques et le coenurus," M4m. Soc. liol., 1855 ; 

 Gaz. Mid., 1852. 



