Mac Diarmida, who starting winning and winning and winning once he was switched to the grass, was euthanized Sept. 8 at Kevin and Jessica Hartigan's Cashel Stud near Ocala, Fla., because of the infirmities of old age. The 30-year-old son of Minnesota Mac had stood his entire career at Cashel.Mac Diarmida was bred by the late Cashel owner John Hartigan and sold privately as a weanling to Dr. J.M. Torsney. After three opening losses on dirt, trainer Scotty Schulhofer tried Mac Diarmida on grass at Hialeah the winter of 1978, and the colt responded with a five-length win. It was the first of 10 straight wins for the 3-year-old sensation.During his streak, Mac Diarmida won such graded stakes as the Secretariat (gr. IIT), Lawrence Realization (gr. IIT), Leonard Richards (gr. IIIT), and Long Branch (gr. IIIT) Stakes, plus the Lexington Handicap (gr. IIT) over budding superstar John Henry.Mac Diarmida lost for the first time on grass that fall in the Man o' War Stakes (gr. IT) to the filly Waya in a third-place finish, but came back to win the Canadian International Championship Stakes (gr. IT) and the Washington, D.C., International (gr. IT), with Waya third. He was an easy choice for 1978 grass champion.Mac Diarmida, who was produced from the Tim Tam mare Flying Tammie, injured a tendon in January of 1979 and was retired to Cashel. He sired just four stakes winners. He is buried at Cashel.