Art or Science Gallery

Diatom detail, SEM

Diatom. Coloured scanning electron micrograph (SEM) of detail of the silica wall of a diatom. Diatoms may be extremely abundant in both freshwater and marine ecosystems; it is estimated that 20% to 25% of all organic carbon fixation on the planet is carried out by diatoms. This is possible because they contain chlorophyll. Diatoms are a major food resource for marine and freshwater microorganisms and animal larvae, and are a major source of atmospheric oxygen. A unique feature of diatom cells is that they are enclosed within a cell wall made of silica (hydrated silicon dioxide) called a frustule. Magnification: x10000 when printed at 10 centimetres wide

© Science Photo Library

Human eye, illustration

Eye anatomy. Cutaway illustration passing through a human eye, showing its internal anatomy and structure. The front of the eye is at right, and the structures here include the cornea, the pupil (surrounded by the iris), and the lens (oval object). Light passes through these, and is focused on the retina (yellow), a layer of light-sensitive cells and blood vessels lining the inside of the eye. The light triggers signals that are passed through the optic nerve to the brain, where they are interpreted to provide vision. The inside of the eye is filled with a clear gel, the vitreous humour. At top and bottom are the eye muscles (muscles of the orbit, red)

Human brain, illustration

Illustration of a cross-section of the brain showing the various lobes. The lobes are shown in different colours - red (frontal), green (parietal), yellow (occipital), orange (temporal), and pink (limbic). Also shown are the various ventricles, the brain stem, the thalamus and hypothalamus, the cerebellum, the pituitary gland and the corpus callosum. The background shows a silhouette of a human skull and head