Who discovered the phenomenon of heterothallism ?

Explanation

**Step-by-Step Solution:**

1. **Understanding Heterothallism**:
- Heterothallism is a biological phenomenon that involves the presence of two or more different mating types or sexes within a species. This is important for sexual reproduction in certain fungi and other organisms.

2. **Identifying the Discoverer**:
- The phenomenon of heterothallism was discovered by a geneticist.

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