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BtTLLETIlSr 1369, XT. S. DEPAETMElSTT OF AGElCtTLTUEE 



most cases applied with the fingers, care being taken to press some 

 of the material into the apertm^es in the skin (fig. 34) . The liquids 

 were applied with hypodermic syringes, a blunt needle being used 

 and care being taken not to injure the grub; with oil cans (fig. 35) ; 

 with eye droppers ; or in the form of a general wash thoroughly ap- 

 plied to the backs of the cattle with a stiff brush. In preliminary 

 tests with all of the materials the cattle were numbered and a dia- 

 gram made of the distribution of the grubs on the back, each grub 

 being numbered and the stage of development determined before 

 the application was made. In some instances the hair was clipped 

 from around the openings in the hide; but the results in each case 

 were checked afterwards by the treatment of other infestations in 



Fig. 34. — Applying- ointment to grubs in back of heifer 



which the hair was left undisturbed immediately around the holes 

 and the position of the grubs marked by clipping the hair below each 

 of them. In injecting the materials into the cysts an effort was made 

 to fill the cavity around the grub with the liquid. The average 

 quantity used was something less than 1 cubic centimeter per grub. 

 In order to determine the results of the treatment in the early experi- 

 ment, each grub was carefully examined from four to six days after 

 the treatment was made. Then the larvae were extracted and notes 

 made on their condition and the condition of the lesions produced by 

 them. Following the preliminary tests, large numbers of grubs were 

 treated without determining the stage they were in or otherwise in- 

 terfering with them before the application. The percentage of mor- 

 tality in some cases was determined merely by continued observation 



