Abstract
THE existence of viruses was first deduced from work done in 1892 on tobacco plants suffering from mosaic, and much of what we now know of these elusive entities has come from further work on this and a few other plant diseases. It is far from certain that this knowledge can safely be applied to the causes of the many diseases, affecting all kinds of animals, higher plants and bacteria, that are now attributed to viruses. These cover a wide range of clinical conditions, and we know for certain of only two features that they have in common; their causes have neither been seen nor cultivated in vitro. If we wish, we can turn these negative features into what looks like a positive statement, by denning viruses as obligately parasitic pathogens too small to be resolved by microscopes using visible light. Indefinite as this is, it may still prove to be more precise than the facts warrant, for obligate parasitism is always postulated rather than proved, and serious attempts at cultivation have actually been made with very few viruses. Thus, when we speak of a virus disease, we usually mean merely an infectious disease with an invisible cause. Unless the resolving power of the microscope has some unsuspected significance in defining biological types, this obviously tells us nothing specific about the nature of viruses and might well cover a range of different entities.
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
BAWDEN, F. Plant Viruses and Virus Diseases*. Nature 155, 156–158 (1945). https://doi.org/10.1038/155156a0
Issue Date:
DOI: https://doi.org/10.1038/155156a0