Red alage: Best observation techniques

The red algae belong almost exclusively to salt water, but a few genera are found only in fresh water, usually in running water, and a few forms occur both in salt and in fresh water. Nearly all are small forms, and for habit work can be floated out and mounted on paper. Very few will need glue or gummed paper.

For more critical habit work and for Venetian turpentine mounts, fix in 6 to 10 per cent formalin in sea-water. Material keeps indefinitely in 10 per cent formalin.

For sections, use the chromo-acetic acid with or without the addition of a little osmic acid, as recommended for the brown algae. The same method of fixing and washing should be used as for the brown algae, except that in the case of the few fresh-water forms, fresh water should be used in making the fixing agent and in washing it out. For Polysiphonia) and doubtless for many other forms, the period in the fixing agent should be very much shortened. Picric acid, corrosive sublimate, and absolute alcohol have been tried, but the results have not been encouraging.

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