154 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



for producing ophthalmic disks has worked satisfactonly and has 

 enabled the laboratories to produce disks in the large numbers 

 shown. 



The quantity of mallein supplied to bureau and to State officials 

 was 7,271 cubic centimeters. 



COOPERATION WITH INSECTICIDE AND FUNGICIDE BOARD. 



One hundred and fourteen samples of insecticides intended for use 

 on domestic animals were examined for the Insecticide and Fungi- 

 cide Board, 9 of which were found to be misbranded and adulterated 

 and 72 misbranded. 



ZOOLOGICAL DIVISION. 



The investigation of parasitic diseases of animals and the study, 

 collection, and determination of animal parasites have been continued 

 in the Zoological Division under Dr. B, H. Ransom, chief. 



ROUNDWORMS OF SHEEP. 



At the bureau farm near Vienna, Va., a test of a method of con- 

 trolling stomach-worm infestation by the administration of 1 per 

 cent copper-sulphate solution at intervals of three weeks throughout 

 the year has given very satisfactory results. There has been no evi- 

 dence of injurious effects upon the sheep, and the number of worms 

 has been diminished almost to the point of disappearance. The de- 

 struction of the worms in the older sheep has correspondingly reduced 

 the infestation of the ground and has thus protected the lambs from 

 picking up the parasites in numbers sufficient to cause any damage 

 up to the time of weaning. Before weaning it has not been found 

 necessary to dose the lambs, although the fact that they have ac- 

 quired a few worms, as shown by the presence of eggs in their feces, 

 shows that to retain control over the parasites it will be necessary to 

 dose them with copper-sulphate solution throughout the summer. 

 The dose of the 1 per cent solution of copper sulphate is 4 fluid ounces 

 for a lamb of 80 pounds or for larger sheep. Lambs of 60 pounds 

 are given 3 ounces, and 70-pound lambs are given 3^ ounces. The 

 dosing of the ewes at three-week intervals is interrupted two weeks 

 before lambing, but is resumed soon afterwards. This method of 

 stomach-worm control — repeated dosing of the entire flock through- 

 out the year — has thus far proved the most satisfactory of any tried. 

 It appears troublesome, but as a matter of fact is easily carried out. 

 As many as 50 sheep can be dosed in an hour, and no preliminary fast- 

 ing of the animals is necessary. It has been found that the method 

 not only keeps stomach worms well under control but reduces the 

 prevalence of nodular worms, various small intestinal nematodes, 

 and tapeworms. 



ROUNDWORMS OF HOGS. 



Investigations have been continued in McLean County, 111., on the 

 practical control of Ascaris infestation. Observations were made on 

 nearly 10,000 pigs reared on 31 farms in the autumn of 1921 and 

 gpring of 1922, following the method of control which lias been 

 under test during the past three years. This method consists in ob- 



