The lucerne spread southward and south-westward from this point; and the improvement of the herds kept pace with it. I have shown elsewhere how this improvement was checked north of a line along the course of the Parana, the northern frontier of the Constitucion and General Lopez departments, in the province of Santa Fe and on the Rio Cuarto, and in the Cordoba province, by the presence of the _garrapate_, which inoculates the cattle with a dreaded disease, Texas fever. The creole cattle are immunized against the _garrapate_, but pedigree cattle quickly succumb to it. In order to protect the southern zone, where the _garrapate_ does not reproduce, the Argentine Government imposes severe restrictions on the transport of cattle from north to south; the cattle have to have disinfectant baths at the frontier-stations. This cuts pastoral Argentina in two. While the Durham cattle of the south are intended for the refrigerators, the creole cattle of the north still supply the _saladeros_, which have disappeared from Buenos Aires, but survive on the Uruguay. Yet the advantages of crossing with European breeds are such that the northern breeders, in spite of the risk and the expense, have not given up all hope of accomplishing it. The transformation of the herd, however, is bound to be very slow. Pedigree breeders are brought from the south and kept in the stable. Their progeny, born on the spot, resist Texas fever better and can be put out to pasture. There has been more progress in the contaminated zone on the right bank of the Parana than in Entre Rios and Corrientes. Pedigree animals have been introduced at Santa Fe, not only in the region of the colonies, but further north, in the extreme northern corner of the Pampa (San Cristobal department), colonized by ranchers from the north of Buenos Aires and the south of Santa Fe, who were ousted by the progress of maize. They have brought with them to the new lands the cultivation of lucerne and the methods they followed on their former property. At Corrientes, on the other hand, breeding is an historic industry. The staff of the ranches is indigenous. The pastoral traditions are unchanged.