Who demonstrated that the extract of the infected plants of tobacco could cause infection in healthy plants ?

Explanation

To answer the question, "Who demonstrated that the extract of the infected plants of tobacco could cause infection in healthy plants?", we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Historical Context**: The question pertains to a significant discovery in the field of plant pathology and virology, specifically regarding tobacco plants.

2. **Recall Key Figures**: The key figure associated with this discovery is M. W. Beijerinck, who conducted experiments in the late 19th century.

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