While the door closes for the moment for one Glasgow Warrior, it springs open for another as Max, the 24-year-old centre/wing, will now join his younger brother Thom on the trip to South America.
Moray sustained an ankle injury playing in Warriors' Magners League victory over Munster in Cork at the weekend. Scotland team doctor James Robson said: "Moray will be subject to further assessment but on reviewing the X-ray he will be in a compression boot for two weeks then undergo a period of rehabilitation of between four to six weeks, which will rule him out of the tour."
Low's place will be taken by the experienced Edinburgh prop Craig Smith, who first toured Argentina as part of the Scotland under-19 squad that also included Chris Paterson in 1997.
Smith was named last week in the Scotland A squad for the Barclay's Churchill Cup in North America next month. A replacement for that squad will be announced later this week.
Meanwhile, two of the casualties among the Scotland backs, Nikki Walker and Rory Lamont, have not recovered in time from leg and knee injuries respectively so will therefore be unable to fill any of the vacancies in the tour party to Argentina.
Scotland coach Frank Hadden said "We have decided to promote Max Evans from the Scotland A squad. Max has played well in the Magners League for Glasgow and is another to have benefited from involvement with both Scotland A and Scotland 7s.
We are still waiting to see if Simon Webster will recover from his hamstring injury to make the tour. He'll be subject to further monitoring and we'd hope to make a decision on Simon next week", Hadden added.
Like Smith, a decision on who replaces Max Evans in the Scotland A squad will be made later this week.