What is Pleurococcus?

This form, which is used everywhere as a laboratory type of the unicellular green algae, is found on the bark of trees, where it is more abundant on the north side and near the ground.

It is also found on stones and fences, and in moist situations generally. It is easily secured in nearly all localities and at all seasons.

The life-history of Pleurococcus is variously described in textbooks, but it is very doubtful whether there is any mode of reproduction except by cell division. The zoospores and gametes which are sometimes described probably belong to other forms which are occasionally associated with Pleurococcus, especially when growing in very moist situations.

A study of the living material is sufficient for any general course. The bright-green cells, scraped off and mounted in a drop of water, show the rather thick wall, the chromatophores, and usually the nucleus. A drop of' iodine will bring out the nucleus, if it does not show already, and will also stain the pyrenoid, if the cell contains one. A mount in Venetian turpentine, stained in Magdala red and anilin blue, shows the nucleus very clearly.

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