plastid

Description:

Pleurosigma (ploo-row-sig-ma) and Gyrosigma are two rather similar genera of sigmoid-shaped pennate diatoms found in intertidal sediments, salt marshes and so on. The nucleus is located at the centre of the cell. The plastids contain chlorophylls a and c which gives the yellowy-brown colour. This picture is taken of the surface of one of the valves and shows the raphe that is used in locomotion, and shows the plastids. Refractile globules are said to be the storage products from excessive photosynthesis. Pleuosigma is distinguished in part by the angled pattern of marks on the valve of the frustule. Differential interference contrast.