A device for transferring, agitating, and sampling blood products sealed in tubes which are grouped together in cassettes wherein each cassette containing sample tubes is extracted from a storage receptacle by a moving loading and ejection carriage which shifts and positions it, using a retractable finger, in the cavity of a rotary carriage. The rotary carriage mixes the samples and stops so that sampling of tubes in the cassette can be performed by a sampling station which is movable in relation to the tubes temporarily immobilized in a vertical position with plugs facing downwards. The device is usable as a hematological analyzer.