PHAEOPHYCEAE 
199 
to the sides so as to form a tripod. Place the bottles or cans of material 
under the pipettes and let sea-water flow into the tub. 
If such chromic-acid material is to be used at once for Venetian 
turpentine mounts, follow the washing in sea-water by \ hour’s 
washing in equal parts sea-water and fresh water (not necessarily 
running water) and then \ hour’s washing in fresh water. The 
material is now ready for an aqueous stain or for 10 per cent glycerin. 
If desirable to keep it for future staining, put it into 5 or 6 per cent 
formalin in fresh water. 
Material for sections may be treated in the same way, but it is 
often better to add 2 to 10 c.c. of 1 per cent osmic acid to 100 c.c. 
of the chromic-acid solution. The 1 per cent osmic acid should be 
made up in distilled water. 
Small filamentous forms, if they are to be mounted whole, are 
usually more satisfactory to handle if fixed in formalin. A strong 
solution, about 10 c.c. of commercial formalin to 90 c.c. of sea-water, 
is very good. Material is well fixed in a few days, but may be left 
here until it is needed. To make preparations, wash in fresh water 
and follow the Venetian turpentine method. 
For habit demonstrations many of the smaller forms can be 
floated out and dried on paper. Ectocarpus, Desmotrichum , Dictyota, 
Cutleria, and even small specimens of Laminaria are quite useful 
when prepared in this way. Take a light pine board, a little larger 
than the standard herbarium sheet, float it in a tub of water, place 
on the board the paper upon which the material is. to be mounted, 
arrange the material with a toothpick or the blunt end of a needle, 
dipping all or a part of the board under water whenever necessary. 
Cover with a piece of cheese-cloth, add a blotter or two, as in case 
of flowering plants, and dry under gentle pressure, changing the 
blotters frequently. The algae have enough mucilage to make them 
adhere to the paper. Coarse forms, like Fucus , may need to be held 
down by strips of gummed paper. 
Sphacelaria.—-The apical cell of Sphacelaria or the nearly related 
Stypocaulon affords an excellent study of the structure of cytoplasm. 
Flemming’s weaker solution, with the osmic acid even a little weaker 
than recommended in the formula, is good for the apical cell and the 
mitotic figures, which are quite conspicuous. For these features 
it is a good plan to break off the tips so as to have only pieces 6 to 
12 mm. long, which will lie flat in the paraffin. The tips should be 
