I believe the choice of Porphyry in the portrait group of tetrarchs speaks to imperial power. Portrait of the Four Tetrarchs is a porphyry sculpture group of four Roman Emperors dating from around 300 AD. The sculptural group has been fixed to a corner of the facade of St mark's Basilica in Vence, Italy since the Middle Ages.
Answer;
-Change in pressure.
Explanation;
-Increasing the pressure on a reaction involving reacting gases increases the rate of reaction. If you increase the pressure of a gas, you squeeze it into a smaller volume.
-When you increase the pressure, the molecules have less space in which they can move. That greater density of molecules increases the number of collisions. When you decrease the pressure, molecules don't hit each other as often and the rate of reaction decreases. Pressure is also related to concentration and volume.
Try researching the discovery of microscopes and their impact on scientific discoveries, including cells!!!
Prokaryotic cells lack a nucleus.