Gregor Mendel, the father of genetics, meticulously controlled the pollination process in his pea plant experiments. Here's how he ensured cross-pollination:

1. Emasculation: He carefully removed the anthers (the male reproductive parts) from the flowers of the plants he wanted to use as the female parent. This prevented the flower from self-pollinating.

2. Cross-Pollination: Mendel then took pollen from the anthers of a different plant (the male parent) and manually transferred it to the stigma (the female part) of the emasculated flower.

3. Controlled Environment: He conducted these experiments in a controlled environment to avoid accidental pollination by insects or wind.

By these steps, Mendel could be sure that the offspring he observed resulted only from the specific cross-pollination he intended. This allowed him to track the inheritance of traits through generations and establish his fundamental laws of inheritance.