398 Journal of Agricultural Research voi. xii. no. 7 



experiments with the more promising. It is therefore possible that some 

 of the drugs tested only once and on a limited number of animals may 

 have more anthelmintic value than the tests indicate. On account of 

 the extent of the field to be covered, the writers did not feel justified in 

 devoting more effort to those drugs which gave small promise of success. 



Some such method as the above has been employed by previous in- 

 vestigators. Hutcheon {iSgiy made numerous tests of anthelmintic 

 treatments for stomach worms in sheep and goats in South Africa, 

 and followed the treatments by post-mortem examinations to determine 

 the immediate effect on the worms. Stiles {1901, 1902) did similar work 

 in this country, and a number of veterinarians and stockmen made investi- 

 gations involving treatment, post-mortem examination, and clinical ob- 

 servation. But, so far as the writers are aware at present, a detailed 

 series of experiments covering the treatment of animals and the collection 

 of all worms from the feces for a number of days up to the time of making 

 a post-mortem examination in which all worms remaining were collected, 

 has not been reported. 



In this work the following method was pursued: The animals were 

 given an appropriate dose of the anthelmintic to be tested, the method 

 of dosage varying with the purpose of the experiment and the substance 

 to be tested, preliminary purgation being undertaken or omitted as de- 

 sired. Treatment was usually administered in the morning, and all feces 

 were collected every morning thereafter until the animal was killed. The 

 feces were washed through a set of graded screens and the screens exam- 

 ined for worms. The animal was usually killed the morning of the fourth 

 day after the administration of the last dose of the anthelmintic, and all 

 parasites remaining were collected and counted.^ The percentage of effi- 

 cacy was then estimated from the number of worms found on post- 

 mortem examination and that number plus the number passed after 

 treatment. When preliminary purgation was resorted to, the feces were 

 collected on the following day, the day of administering the anthelmintic, 

 to ascertain what worms if any were removed by simple purgation. 



For convenience we have arranged our experimental data in three 

 groups: (i) Simple purgatives, (2) a group including anthelmintic shaving 

 a mineral base and coal-tar products, and (3) a group covering the vege- 

 table anthelmintics. Tables I to V of the discussion of results summarize 

 the results of the experiments. 



' Bibliographic citations in parentheses refer to " Literature cited." p. 446-447. 



' In conducting these experiments the writers occasionally found on post-mortem examination dead 

 worms in the large intestine or rectum which normally are found in the small intestine. In such cases, 

 as the worms were evidently in the process of passing out, they are credited as being removed by the an- 

 thelmintic. 



