Microscope

Light microscopes use lenses to form enlarged images; a compound instrument normally combines objective and eyepiece lenses. Magnification concerns apparent size, while resolution concerns distinguishing nearby details. Enlarging a blurred image adds no new structure. Illumination, lens quality and specimen thickness all affect what can actually be observed.

References: [1]

Hooke’s Micrographia, published in 1665, used detailed illustrations to communicate observations of insects, plant material and other small objects. Adjusting instruments, drawing, naming and describing were linked activities. His term cell described compartments in cork; it did not amount to the complete cell theory developed in the nineteenth century.

References: [2]

Many cells are nearly transparent. Sectioning, staining and contrast methods reveal structures but may alter or damage specimens. A micrograph therefore has a preparation history. Researchers need to explain fixation, cutting and staining and consider possible artefacts, choosing methods appropriate to the biological question rather than treating every image identically.

References: [1]

Electron microscopes use electrons instead of visible light and investigate finer structures, generally requiring vacuum conditions and specialized preparation. Suitable light methods can observe living material. The techniques are complementary rather than a simple succession of obsolete and superior devices: they provide different scales, specimen conditions and kinds of information.

References: [1]