A pipette includes a tubular body having an internal passage, a first end and a second end. The tubular body is deformed inward to create a narrow constriction or slit within the internal passage of the pipette. When vacuum is applied to the pipette and a solution is drawn into the pipette, the slit increases the velocity of the solution while gently deforming and separating clumps of matter (e.g., colonies of bacteria) contained in the solution. As the deformed bacterial colony passes through the slit, the bacteria solution is mixed due to turbulent flow within the pipette created by the increase in velocity. Bacteria colony size is further reduced by alternating the pipette flow direction to cycle the bacteria through the slit two or more times. A sloped entrance to the slit also prevents the oily bacteria from clogging the slit during cycle reversals.