Flatworms possess excretory organs known as nephridia. Specifically as annelids, flatworms possess a variant known as metanephridia.
Due to a law being a predicted sort of event that is bound to happen every time, a pattern, we can say that since the cell theory is a pattern instead of a possible explanation, it can be a law. However, since we don't have an accurate explanation to the part which claims that they all come from pre-existing cells, it is a theory, we don't have enough information to confirm that the theory is a solid fact, therefore, we can't confirm that it is a law.
English: Density is MassUnit Volume; relative density is the density compared to a reference substance (usually water) under standard conditions.
Nepali: घनत्व मास एकाई भोल्यूम हो; सापेक्ष घनत्व मानक अवस्था अन्तर्गत सन्दर्भ पदार्थ (सामान्यतया पानी) को तुलनामा घनत्व हो।
