When we see chiasmata under a microscope, that lets us know that prophase I has occurred. During this phase of meiosis, the nuclear envelope breaks up and disappears, and so does nucleolus. The chromosomes become visible at this point.
Answer:
Aristotle
Explanation:
Aristotle was the first person to study the embryos of different species.
Has reached it's tipping point, I think. Your question was not very specific, so hope this helps.
Nitrification or nitrogen fixation