CESTODA 12 i 



grand-daughter vesicles, constantly developing in their interior 

 secondary and tertiary brood-capsules and scolices, but some- 

 times, it would appear, developing neither the one nor the other. 

 This is the view of Naunyn, which is somewhat opposed by 

 Leuckart, who holds that the vesicles ordinarily arise from within 

 the layers of the ectocyst. Speaking of these daughter-hydatids 

 Leuckart remarks that " Naunyn denies that they take their 

 origin between the lamellae of the mother bladder a fact, how- 

 ever, which, in agreement with Kuhl and Davaine, I have seen 

 more than once and have followed out step by step." For my 

 own part I incline to the belief that the process as observed by 

 Leuckart is exceptional, and that under ordinary circumstances 

 it occurs as Naunyn has described it. Thus the long and short 

 of the whole matter appears to be that the endocyst is capable 

 of forming solitary scolices. Some of the scolices become 

 differentiated to form brood-capsules, a portion of whose indi- 

 vidual echinococcus-heads may, in their turn, become secondary 

 brood-capsules, whilst others fail to become either scolices or 

 brood-capsules. It accords with our knowledge of the general 

 plan of development to believe that the daughter and grand- 

 daughter hydatids are likewise peculiarly modified scolices. 

 They are, in short, buds of the endocyst. 



The distribution of hydatids throughout the organs of the 

 bearer, and their prevalence in particular countries, has espe- 

 cially engaged my attention. I have personally examined 

 upwards of a thousand preparations of entozoa in our public 

 collections ; and of these, 788 are preserved in the anatomical and 

 pathological museums of the metropolis. By this inspection I 

 have obtained a tolerably accurate knowledge of the pathology, 

 localisation and effects produced by the presence of bladder- 

 worms in at least 200 unpublished cases of hydatid disease. 

 Most of our museums exhibit one or more specimens that are 

 unique. After making certain necessary deductions, I find that 

 I have 192 new cases to add to the 135 cases of hydatid 

 disease that I had previously recorded, affording a total of 327 

 cases available for statistical purposes. If an analysis of these 

 cases be made and compared with the statistics furnished by 

 Davaine, and if the whole be reduced to the lowest number of 

 practically available terms, we at length obtain a result which, 

 although it may be only approximatively correct, is nevertheless 

 of much practical value and significance. The statistics in 

 question stand as follows : 



