Final answer:
Heparin is the preferred anticoagulant used to prevent clotting in mammalian blood samples for hematologic analysis.
Step-by-step explanation:
The preferred anticoagulant used to prevent clotting in mammalian blood samples destined for hematologic analysis is Heparin.
Heparin is a short-acting anticoagulant that is stored in mast cells and released when tissues are injured. It opposes the conversion of prothrombin to thrombin and is found on the surfaces of cells lining the blood vessels.
Other anticoagulants such as Ethanol, Aspirin, and EDTA are not typically used for preventing clotting in blood samples for hematologic analysis.