8 



limited ia comparison with tlie flocks which graze upon them. Under 

 such conditions parasites multiply more rapidly, and their ravages be- 

 come more alarming. For this reason the time has come when we must 

 pay more attention to these organisms and study more assiduously the 

 means of controlling them, if we would preserve that healthfulness and 

 vigor for which the animals of this country have heretofore been noted. 

 It is hoped that the systematic treatment of the subject presented in 

 the accompanying volume may assist in accomplishing this object. 

 Very respectfully, 



D. E. SALMON, 

 Chief of the Bureau of Animal Industry. 



Hon. J. M. Rusk, 



Secretary of Agriculture. 



