139 
be considered as certain that no Opisthorchis species occurs in 
mammals and Man in Egypt and the inference therefrom must 1 think 
be that the Avian Opisthorchis which is indigenous in this country 
cannot be the same species which inhabits mammals and Man in 
Europe—all the resemblance they show in their internal organisation 
notwithstanding. 
The case of Opisthorchis felineus and Opisthorchis gem mu s is 
not the only one known; but this as well as the corresponding 
instances tend to show that, in the case of the two Opisthorchis 
sinensis- forms also, the internal similarity must not necessanl) be a 
proof of their specific identity—the less so, as in the size of their 
bodies and the ratio of their suckers characters are given which 
practically allow a differentiation of the two forms. 
A second point which seems to me very important is the iact that 
the two varieties of Opisthorchis sinensis not unfrequently occur quite 
separately. It has already been pointed out that the large vanct) 
was present alone in the three cases mentioned above; but the same 
fact may be inferred from some earlier cases on record. The parasite 
was discovered in 1874 by McCoNNELL; the measurements given of 
the worms by the author are x 7 tj in. for the length and ) in. for the 
breadth, this would correspond to 17-8 and 3-03111111. respectively 
and is, as may be mentioned here in anticipation, exactly the size of 
the specimens 1 at present possess of the large variety.The author 
*It is perhaps not out of place here to draw attention to the fact that the sire 
of preserved specimens of parasitic worms is within certain limits influenced b) the 
metnods of preservation on the one hand, and by their own condition at the moment 
of preservation on the other. If specimens are collected from a living or recent 1 > 
killed host, they are still alive ; if they remain in the organs after the death of their 
host they will die, too, after a shorter or longer time; the same thing happens when 
living parasites are brought into water, which is very harmful to them and destroys 
certain species very quickly. Before death they stretch themselves to their full 
size, and the commencing decomposition even makes them swell somew hat. Living 
parasites, when preserved immediately after removal from their natural habitat, 
always react by a contraction, which is the stronger the slower the preserving 
leagent acts upon them. Specimens which have died—in water or in the organs 
°‘ tlie * r hosts (as is usually the case in post-mortem examinations made some time 
alter death and in warm climates)—do no longer contract, but may shrink more or 
ess according to the dehydrating power of the preserving fluid. All these factors, 
eretore, have their influence upon the dimensions the specimens exhibit alter 
preservation, and it is necessary to remember this fact when the size of a 1 ertain 
P ecies IS . used as one of its distinctive characters. However, the changes due to 
preservation always keep within certain narrow limits, and can even be fixed b\ 
ac ual observation. The parasites of the Port Said case were obviouslv dead when 
tney came into contact with the preserving fluid, for they are not contracted. 1 h. 
nuid used had been formaline, which does not dehydrate: thus, the snecimen* «h,.u 
1 - » -UrtW icauicu 00 
shrunk to a length of 14 to 16mm., but could be made to 
termer length again by placing them hack into formaline. 
