The Rot in Sheep. 



17 



the water has drawn away, they will perish in time by frost or desiccation, 

 and then the meadow becomes safe pasturage for sheep ; but for a long time 

 whilst thev arc moist, and for a short time after they are dry, these eggs retain 

 their vitality. The period, at which their vitality becomes extinct I have been 

 unable to ascertain. 



"This is, however, a point of considerable importance to flock -owners to 

 enable them to judge with some precision when they may safely venture to 

 depasture meadows subject to floods. If attention be directed, to this point, 

 accidental occurrences and casual observation may elicit facts which will 

 throw light upon the subject." 



This theory of the introduction of the ova of flukes leading to 

 the existence of the entozoa in. the bile-ducts would certainly 

 appear at first sight to have a good foundation ; but it has been 

 fully ascertained that it also fails to account for sheep becoming 

 rotten. " 



As far back as 1852 we put this theory to the test of direct 

 experiment. We collected a much larger number of eggs, fresh 

 from the biliary ducts and intestines, and therefore in their per- 

 fected condition, than it would be thought possible that a sheep 

 could obtain during many weeks' grazing, and exhibited them 

 to an animal, using a little water as a vehicle. The quantity 

 was not less than a teaspoonful ; and as it is often impossible 

 to count the number of ova in the field of the microscope, which 

 may be contained in a drop or two of water, it can be easily 

 understood that hundreds of thousands were thus given to the 

 animal. The sheep was kept six months before being destroyed, 

 and, on examining its liver and other organs, not a single fluke 

 was found, nor any traces of disease of liver. This negative result 

 was exceedingly valuable, and it fully confirms similar experi- 

 ments which have been carried out in Germany and elsewhere. 



Gerlach, who was connected with the Berlin School of 

 Veterinary Medicine at the time, had recourse to experiments of 

 the same kind as ourselves, and invariably with a like result ; 

 thus again showing that the ova of flukes, when directly intro- 

 duced into the digestive system of the sheep, fail to become 

 developed into perfect entozoa. It may be said that we have 

 almost a continuous proof of the correctness of this conclusion 

 in the enormous quantities of fluke eggs which enter the 

 stomach and intestines of dogs belonging to butchers, farmers, 

 and others, from eating the livers of rotten sheep. Such animals 

 suffer no ill effects therefrom, and we have never met with flukes 

 in the biliary ducts of the dog, although our opportunities 

 have not been a few in making autopsies of this animal. No 

 doubt some persons will object to this illustrative comparison, 

 on the ground that the dog is a carnivorous animal, and there- 

 fore products of this or any similar description would be 

 quickly digested in his stomach. We admit the force of the 



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