To save researchers time and increase the accuracy of the experiment are brilliant, I'm not afraid of this word, minds came up with a cathode-ray tube. The idea of his work is simple - we direct the beam to the viewing field, and set the counter, what will the ray do when it hits the cell? The ray will reflect from it and get on the counter, which summarizes all the reflections. The method has only 1 lack - the beam is reflected equally from both dead and living cells.