PHAEOPHYCEAE 241 



its destination, where it should be put into the formalin mixture. This 

 method reduces the cost of transportation. 



These large forms, after a week in the fixing agent, may be rinsed 

 in water and then soaked in equal parts of glycerin and water, using 

 just enough glycerin to make the plants flexible, not enough to make 

 them wet to handle. In this way, material of Laminaria, Nereocystis, 

 Macrocystis, Postelsia, and other coarse forms have been kept for 

 years. When not in use, they should be kept stored in a box. 



For habit demonstrations many of the smaller forms can be floated 

 out and dried on paper. Ectocarpus, Desmotrichum, Didyota, Cutleria, 

 and even small specimens of Laminaria, Nereocystis, and Macrocystis 

 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 neces- 

 sary. 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 and Ascophyllum will 

 have to be fastened to the herbarium sheet with gummed paper. 



For material to be mounted by the Venetian turpentine method, 10 

 per cent formalin in sea water is a good fixing agent. There should not 

 be any acetic acid in the reagent, unless you desire to dissolve away 

 the mucilaginous coating which all these algae have, if they feel slip- 

 pery. Wash in sea water 24 hours, then in equal parts sea water and 

 fresh water for 1 hour, and then for 1 hour in fresh water. 



If material is to be mounted whole, it is usually stained at this 

 point and put into Venetian turpentine. A longer method, while tedi- 

 ous, gives so much better results, especially with delicate forms, that 

 it is worth the extra labor. Run the material up through the series of 

 alcohols to 85 per cent, as recommended under the Venetian turpen- 

 tine method. Leave it in 85 per cent for 2 days to harden; then run it 

 back slowly to water. Stain and put it into 10 per cent glycerin and 

 follow the usual Venetian turpentine method. If phloxine and anilin 

 blue are to be used, the material can be run up to 85 per cent alcohol, 

 then stained in the usual way. Or, after washing in water, the regular 

 Venetian turpentine method can be followed. 



Sphacelaria. — The apical cell of Sphacelaria or the nearly related 



