122 
EDITORIAL OBSERVATIONS. 
a short time assume an independent existence, swimming 
about in water holes and wandering over marshes and all 
moist pastures, especially whilst the dew is heavy on the 
grass, until at length they are taken into the stomach of the 
sheep or other herbivorous animals when the latter are 
feeding or drinking. Dr. Cobbold adds, that it is not im¬ 
probable they may sometimes be swallowed when they are 
in the body of their host, and I incline to think that this is 
the usual condition in which they enter the rumen of the 
sheep. Be that as it may, the worms soon fasten themselves 
on the coat of the stomach of their new landlord, by means 
of a sucker provided for the purpose, and bore their way 
through the tissues to the liver, where they lose their tail, 
and become encysted for some weeks or even months before 
they are converted into perfect flukes as found in the biliary 
ducts. The bile appears to be their natural food, for in 
the ducts they thrive rapidly, attaining the length of one 
inch and even a larger size. Here also they begin to expel 
in large quantities, though only one at a time, their ova, 
which escape by the common duct of the liver into the intes¬ 
tine, and are thus transmitted to the pastures, to be again 
transformed into fluke by the process already explained/* 
“ On the primary origin of flukes Dr. Cobbold gives no 
opinion. Very little, if anything, is known on that subject; 
it is the general belief of all students of nature that, like the 
acari, and all other parasites, flukes are not a spontaneous 
production. As I have before stated, my own observations 
confirm, with the single exception noted below, the perfect 
accuracy of Dr. Cobbold ; s theory, and on its basis only can 
any remedial or prophylactic treatment of the disease be 
entertained. The existence of fluke in the north-eastern 
district is contemporaneous with the introduction of strange 
sheep. Jt was unknown here until about the year 1855, 
and followed very ‘soon after the importation of the first 
German rams and the introduction of some other sheep from 
localities where fluke was known previously to have prevailed; 
it is noteworthy that those flocks amongst which have been 
introduced the fewest strange sheep are the last and the least 
affected by this disease. It thus appears from Dr. Cobbold's 
explanation and other data that two conditions are absolutely 
