In the human body, almost everybody organ has some system or physiological process that is highly sensitive to random pH changes. Digestion is one of the major physiological processes that also affected by pH fluctuations.
If there is a change in the pH, it will directly affect the process of digestion. The acid that is released by the stomach in the process of digestion is neutralized by the nervous system.
The substage condenser is either incorrectly positioned or the light stop is the wrong size for the objective- or there me be a smudge/mark on the eyepiece
