Contagium vivum fluidum is a term used to describe the presence of a living, infectious fluid in organisms. The proposal of Contagium vivum fluidum was made by M.W. Beijerinck, not D.J. Ivanowsky or Stanley or Robert Hooke.

- M.W. Beijerinck: Martinus Willem Beijerinck was a Dutch microbiologist who made significant contributions to the field of virology. He proposed the concept of contagium vivum fluidum in 1898 based on his studies on the tobacco mosaic disease.

- Tobacco Mosaic Disease: Beijerinck observed that the infectious agent responsible for the disease was smaller than bacteria and could not be cultured using the methods available at that time. He hypothesized that the disease was caused by a living, infectious fluid which he named contagium vivum fluidum.

- Viruses: Beijerinck's proposal laid the foundation for the understanding of viruses as a distinct class of infectious agents. He recognized that viruses were different from bacteria and other microorganisms due to their small size and inability to replicate outside of host cells.

- Key Contributions: Beijerinck's work on contagium vivum fluidum led to the development of new techniques for studying viruses, including the use of filters to separate the infectious fluid from bacteria. He also coined the term "virus" to describe these infectious agents.

- Continued Research: Beijerinck's discovery paved the way for further research on viruses and their role in causing diseases. Today, viruses are known to infect all types of organisms, including animals, plants, and even bacteria.

In conclusion, M.W. Beijerinck proposed the concept of contagium vivum fluidum based on his studies on the tobacco mosaic disease. His work laid the foundation for the understanding of viruses as distinct infectious agents and contributed significantly to the field of virology.

B) M.W.Beijerinck