i88 
cannot quite believe that a close examination would not for ail' 
have resulted in tlie detection of some eggs in the tissue of ik 
bladder. It would Imve been of the utmost interest to know of 
type they were, ('ases like LktuM-Es arc rare in Egypt. bef*C' 
of lire specially favourable conditions for infection in tins coontn 
But other observers may lia\ e an easier opjX)rlunity of examinm 
them. Instead of a tedious preparation of sections, it would sofiit 
to macerate a piece of the bladder-wall in caustic )X)tash, and examii 
the residue. Tlie shells of the Bilhar/ia eggs are not at once dissohe 
by this reagent, and even a few eggs would be found witk 
difficulty, if present. 
The conditions unfavourable for infection as they were suggNr' 
above will in general obtain in countries where there is a iv: 
population, w'here the people do not come regularly in contact wi* 
water every day for a long part of the year, where they are not in ik 
habit of working (or bathing) in companies, where there is not mu- 
water, or where the water, though abundant, flows quickly, &c, 
I know neither the country jior the habits of the population in Soot' 
Africa, in Uganda, in the Congo Free State, or in tlic West Indte. 
but I am fairly sure that on close observation of details the 
aspect of the disease will be found to vary in accordance with il" 
conditions for infection as they have been specified above. 
I have previously alluded to the relative value of statistio- 
observations. I can now illustrate what has been said there by » 
matructive example. Holcomb (who believes in ' ScA. maiisoni 
a ter having given an extensive account of the cases of intestiM 
arziosis obser\cd in tropical America, compares them with tk 
^ '^■Jirious observers on the relative frequenc}-^ 
^ u\ forms of Egyptian Bilharziosis (1907, p. 50). The 
case because there is in Cairo on an average oof 
exneri to 1/ cases of vesical Biliiarziosis, one ought 1* 
the s^lr.e^ Indies, if the cause of the disease wf« 
however '** countries. The actual observalhx 
the vesirni contrary: the intestinal form is veiy common . 
For m. another species of jjarasitc. 
bare fact that thrditp^'^^’^u beyond the 
ase shows in the two countries a remarkabej 
