Protozoan Cattle Fever. Texas Fever. Pahidism of Cattle. 563 



The picking will safely remove all the larger larvae, and the 

 mature ticks which are ready to lay their eggs, but it cannot be 

 implicitly trusted to remove also the all but invisible embryos 

 or seed ticks, and if the host is preserved these grow up and 

 mature, while if they are accidentally dropped or brushed from 

 the surface, they climb upon the first available ox and mature on 

 that. By passing from ox to ox they may be kept alive for a 

 time in the pens adjoining the slaughter house, but fortunately 

 they do not travel over a few feet and if no cattle escape from 

 such pens there is small risk of their preservation. 



Dipping or smearing to destroy the seed ticks on the skin be- 

 comes an essential adjunct to, or substitute for, picking. The 

 Bureau of Animal Industry has experimented largely on dips 

 with most important and valuable results, even if they have 

 proved only in a measure successful and desirable. Aqueous 

 dips they early discarded. Poisonous agents like corrosive sub- 

 limate and arsenic are liable to poison through absorption and 

 licking, with the added drawback that neither these nor calcium 

 sulphide are at all effective in destroying the ticks. Proprietary 

 sheep dips were abandoned on similar grounds. Baths of cotton 

 seed oil were introduced by Francis, but proved not quite effective 

 even when phenic acid, benzine, gasoline, or different mineral 

 oils were added. Paraffin oil gave the best results, and later a 

 staple sold as extra dynamo oil, which in combination with sul- 

 phur (1 : 100) proved most destructive to the ticks, was adopted. 

 But in the hot season, when such dipping is required, any one of 

 these baths produced heating, and illness in the cattle, and 

 together with the exertion and excitement served to rouse into 

 dangerous activity the germs already present in the blood. Oph- 

 thalmia, too, was a very frequent result. If the cattle could be 

 kept on their native pastures the dipping might be permissible, 

 but this was to lose the object aimed at — the wholesomeness of 

 these cattle on uninfected ranges. When shipped north in the 

 hot weather the losses were so great as to be prohibitory. 



If, however, it could be reserved for use on the southern pas- 

 tures, to prevent the maturing of the ticks and the laying of eggs 

 for a future generation, it might be employed to rid the infested 

 pastures of the boophilus, and consequently of infection. The 

 question, then, is reduced to the comparative advantage of the 



