Thoroughbred Racing Stock - The Authentic Origin of Pure Blood Lady Wentworth, 1938 Hardcover, 475 pgs. + 388 half tone & 21 color plates & diagrams in text, fold out map, some rust marks and annotation by previous owner. 1st Edition. Sweeping history of the origin of the thoroughbred, this huge volume is considered somewhat controversial and colored by Lady Wentworth's interests in Arabian horses.