On the shallow bottoms of our sheltered beaches here one can often pick up a stone that is covered with a colony of Acetabularia, sometimes called "the mermaid's wine glass." These delightful alga organisms are a few centimeters tall, and attach themselves with a stalk and rootlike fibers to the rocky substrate. What is remarkable about them is that each "wineglass" is a single cell.
Yes. We are used to thinking of cells as microscopic, but here are cells one can hold between the fingers.
Acetabularia played an important role in the history of genetics. In the 1930s, the Danish biologist Joachim Hammerling used acetabularia to prove that genetic information is stored in the nuclei of eukaryotic cells. The experiments were simple and elegant, science at its best. You can read about them here.
From such simple beginnings did our present awesome power over the genes derive. In the face of such power, we should exercise cautious restraint. We have been wonderfully successful at unraveling the biological secrets of life, but that knowledge does not convey moral wisdom. Erwin Chargaff, a contemporary of Hammerling's and another genetic pioneer, lived long enough to see the birth of genetic engineering. In his memoir, he cautioned against overreaching: "A balance that does not tremble cannot weigh. A man who does not tremble cannot live."