Images Dated 14th October 1998

Coloured SEM of some nerve fibres

Nerve fibres. Coloured scanning electron micrograph (SEM) of some nerve fibres. A group of nerves such as this is known as a fasciculus. Each nerve fibre consists of a nerve cell axon, the output process of a nerve cell, covered in an insulating fatty layer known as a myelin sheath (yellow). Myelin isolates the nerve from its surroundings and helps the nerve transmit its signals more quickly. Nerves in the body serve to collect, interpret and relay information. The nerve fibres are used to pass the information on to other parts of the body, such as the muscles and the organs. Magnification unknown

© STEVE GSCHMEISSNER/SCIENCE PHOTO LIBRARY

Computer artwork of Mendels First Law

Mendel's First Law. Computer artwork of Mendel's First Law, the genetic law of segregation. It was formulated by the Austrian botanist Gregor Johann Mendel (1822-1884), top left, after breeding garden peas (Pisum sp.). Here violet and white flowered parents produce a first generation (F1) with violet flowers. Self-pollinating these gives a 3:1 ratio of violet to white flowers (F2). Each parent has a pair of alleles controlling flower colour. In reproduction, one allele from each parent is randomly picked to help form a daughter plant. The allele for violet flowers is dominant and "masks" all the white alleles in F1. However in F2, 1/4 of the plants have two white alleles

© LAGUNA DESIGN/SCIENCE PHOTO LIBRARY