Stool contains numerous sloughed intestinal epithelial cells, a reliable source of DNA for non-invasive genotyping. ... The droppings were scooped up into a 1.5-ml micro-centrifuge tube ...

A cardboard centrifuge separates blood cells from plasma String ... (of blood, urine, sputum and stool) for analysis. Tests to spot HIV, malaria and ... sandwiching the tubes between them.