The passage discusses the significant contributions and advancements in plant virus research at the Cambridge laboratories, particularly from 1935 onwards. Initially, the focus was on disease symptoms and their insect vectors, but the isolation of tobacco mosaic virus by Stanley in 1935 marked a shift towards studying the viruses themselves. Key discoveries include the identification of the aphid as a major vector, the discovery of the paracrinkle virus, and the analysis of plant virus complexes. The text also highlights the isolation of viruses like potato virus X, tomato spotted wilt, and tobacco necrosis, and the development of techniques such as plant virus serology. Additionally, it mentions the discovery of new viruses like turnip yellow mosaic virus, which is transmitted by a flea-beetle, and the use of electron microscopy to study virus structures. The passage concludes with a new microscopic principle proposed by Dr. D. Gabor, which aims to improve the resolving power of electron microscopes by eliminating the need for objectives, using a two-step process of electronic analysis and optical synthesis.The passage discusses the significant contributions and advancements in plant virus research at the Cambridge laboratories, particularly from 1935 onwards. Initially, the focus was on disease symptoms and their insect vectors, but the isolation of tobacco mosaic virus by Stanley in 1935 marked a shift towards studying the viruses themselves. Key discoveries include the identification of the aphid as a major vector, the discovery of the paracrinkle virus, and the analysis of plant virus complexes. The text also highlights the isolation of viruses like potato virus X, tomato spotted wilt, and tobacco necrosis, and the development of techniques such as plant virus serology. Additionally, it mentions the discovery of new viruses like turnip yellow mosaic virus, which is transmitted by a flea-beetle, and the use of electron microscopy to study virus structures. The passage concludes with a new microscopic principle proposed by Dr. D. Gabor, which aims to improve the resolving power of electron microscopes by eliminating the need for objectives, using a two-step process of electronic analysis and optical synthesis.