 What is distinctive of mechanistic explanations is that they decompose mechanisms into parts or entities and the operations or activities that contribute to realizing the phenomenon. Although sometimes researchers can proceed by reasoning a priori about what component activities would be required to produce a given phenomenon, most often the decomposition is developed on the basis of experiments. While the goal is to identify both parts and operations and to link them, a given group of researchers may only have research techniques that allow them to identify one or the other. This was the case in cell biology. As discussed in  Section 1,  microscopic research enabled researchers to identify component parts (organelles) of cells, but except for indirect clues such as shape or the ability of an organelle to take up a stain, these researchers were unable to procure information about the functions they performed. Biochemists on the other hand were able to identify reactions involved in many cell activities, but since they studied these in chemical soups made by grinding up the cell, they were not able to link these to cell structures. Cell biology developed with the introduction of new techniques such as cell fractionation and electron microscopy that opened up the possibility of localizing biochemical reactions in organelles.