such a ruling would be less defensible than the other alternative, viz 
to declare them as separate species. 
I am pretty certain that many of my fellow-helminthologists will 
think I am pushing things too far, and that what I am about to do 
here is nothing but “species-manufacturing" In order to meet this 
reproach as far as I can, I may be permitted to give my reason; 
somewhat in detail. 
To begin with, it is a fact acknowledged by all observers who have 
dealt with this particular group of parasites (BRAUN, LUEHE 
Muehling, LOOSS) that the members of the genus Opisthorchis w 
in many instances by no means easily to be distinguished. As one 
out of several examples I will mention the case of Opisthorckis 
/ el incus and O pisthorchis geminus , a case observed by myself. The 
former species is in Europe a rather common parasite in the liver of 
certain beasts ol prey, and especially in cats, and is in eastern Europe 
even a not uncommon occasional parasite of man. 0 pisthorchis gemim 
inhabits in Egypt the liver of certain birds ( Milvus aegyptius, the 
common Egyptian kite, Circus aeruginosus, a glede, and Ante 
bonhas fera , the wild duck). It resembles 0 pisthorchis felinW 
anatomically to such an extent that the two forms are hardly 
distinguishable from one another without knowledge of host and 
oca lty. Their internal organisation, therefore, would not furnish 
jectionable reasons for separating them specifically; nevertheless, 
y must be considered as specifically different on biological grounds 
imnn i i VC mUSt ac * n ” t as true cert ain circumstances which are almost 
.possible to comprehend. Among the hosts of 0 pisthorchis grndm 
and thus f*P /lus > s a true Egyptian who never leaves the country 
.hcoILm T qmre hiS paiasites '« B »‘ if * does, it would b 
actually Sha "" u d ° gS ’ C3tS *“* even Man — ll0 sts that in EgJP 1 
also tV":;; ° ther f SPGCleS ° f P ara sites—should not p,ck then, « 
the ^Ptian WrdranTthaTonheE EUr ° Pe ' * f **“ 
°ne and the same - ot * le European mammals were indeed 
any trace of an OpiThorchi, however ' have I in Egypt found 
domestic; nor in Man - 1 ° rm 111 can ^ ne or feline animals, wilder 
ever there was an occ' ' 10U ^' * * lave purposely looked for them when- 
with in the last ten ve^ 0 !! ’ n ° r haVC the P rofess ors of pathology who 
Kasr-el-Aini Hosnitnl S av< ~ mac * e t,le post-mortem examinations at 
° 1CGd an y thin g of the sort. It can therefore 
