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of 1883-84, that these tape- worms were a cause of the larger part of 

 the losses amoag sheep, and urged the necessity of a closer study of the 

 subject, in order that more might be learned of the parasite, the amount 

 of loss it caused, and the means of preventing it. These losses had 

 previously been attributed to a weed called " loco," which the sheep ate. 



In obedience to instructions received from the Commissioner of Agri- 

 culture, the writer proceeded to Colorado in August, 1886, and began a 

 study of the various intestinal parasites of sheep. The studies of that 

 year were pursued, by invitation, on the ranch of Mrs. Mary L. Givens, 

 who, at great inconvenience to herself, did all in her power to aid me. 

 In the spring of 1887 1 again visited Colorado Springs and prosecuted 

 other experiments, which it was hardly possible to conduct in the East. 



Early in my investigations the fact was recognized that one twnia, 

 identified as Tcenia Jimbriata, Diesing, was the most abundant; that it 

 was scarcely ever absent in sheep examined, and was the probable 

 cause of most of the tape-worm disease of Western sheep. As this 

 twnia was so constantly present attention was directed to it, and an 

 endeavor made to obtain it in all of its stages, and to learn how and 

 where it passed its entire life. Another fact was soon learned, that the 

 other species of tape- worm (Tcenia expansa), usually abundant in lambs, 

 was found so infrequently that it was difficult to find sufficient material 

 for study. The methods of study were, first, observation, and, second, 

 experimentation; The experiments have, as yet, been productive of 

 nothing but negative results. In. determining so much of the life his- 

 tory as lias been learned posi-morfem observations have been the most 

 useful. Not only have animals been slaughtered on the ranch for this 

 purpose, but advantages offered by inspections of sheep slaughtered at 

 the shambles for consumption have been utilized. From these inspec- 

 tions the abundance of the parasite, the first appearance in lambs, the 

 different stages in growth, etc., coald be learned, but it soon came to 

 be necessary to study the surroundings of the sheep — the corral, the 

 watering places, and the range — to learn under what condition the par- 

 asite must exist while external to the sheep, i. e., while passing from 

 sheep to sheep. 



The effects of the parasite on its host (the sheep) were arrived at 

 from studies of the iiocks and from observation of individuals at 'post- 

 mortems. The changes found were noted and careful a|ttention paid to 

 the ijoint whether certain changes were due to parasites or another dis- 

 ease called " loco." As all of the sheep examined were called " locos," 

 it is evident that there was here a source of error. No certain patho- 

 gnomonic lesion of" loco " was learned ; as all of the " locos " were in- 

 fected with twnice, the separation of characters due to each disease 

 was difficult. Indeed, it has seemed to me that all of the symjitoms 

 due to the parasitic disease may be ascribed to " loco." The characters 

 of the tape-worm disease are, however, well marked in lambs which 

 have never learned to eat this weed exclusively, and thus could be 



