In London, a traction of only about 2,000 lbs. is required of a draft-horse. In Paris, the horses harnessed to the heavy stone carts are required to drag as much as 5,000 lbs. each, and often even more. What will dealers in heavy draft-horses do? The trade is already taxed to supply the demand. For long experience has taught, and unjudicious crosses have proved the English horse and his derivatives to be unfit for this purpose, for they are too nervous and not sufficiently staunch. Thus, the trade avoids them by instinct, and by instinct avoids every thing resembling them. And, on the other hand, it seizes hold of and clings eagerly to every indication that can serve it as a sign or mark—every thing that can guide it in the search for what it likes, and every thing that can guard against its opposite. Hence, it repels and proscribes the dark-colored coats without examination and reflection, because they are considered the colors of the English horse; it accepts the grays with confidence, because with them it perceives the absence of the dreaded blood, and in them it has found that which satisfies all its wants. Would we have arrived at this point if we had been prudent, and had the cross-breeding been better understood? Finally, what is there at the end of this negative pole and this positive pole? There is the Percheron on whom has devolved, and will devolve for a long time yet, the rude and killing mission of executing the feats of strength exacted of him by modern civilization. The profits in supplying the demand, accrue, and will accrue for a long time to the producer. Thus so long as machinery does not replace the horse in the traction of heavy carriages, so long as the necessity for hard labor remains, requiring strength, intelligence, endurance, and willingness, so long to the Percheron alone will be reserved the dangerous honor of being the great draft power, and the price of this matchless agent will increase in proportion to the growing impossibility of finding his substitute. It is now the time, while crossing the active and trotting breeds with the Arab or with the well-chosen English horse, to carefully preserve the heavy draft-horse, and, by means of persevering and judicious crossing, retain for him his marked superiority. These crossings, which I will sum up in concluding, may find a powerful aid in the creation of a Stud-book of the Percheron breed. CHAPTER IX. IMPROVEMENT BY MEANS OF THE STUD-BOOK.