HOW TO KNOW THE SEAWEEDS 



Bulky specimens, especially calcareous forms and crustose species 

 adhering to rocks, shells, etc., may best be kept in small boxes fitting 

 into standardized cardboard trays. The trays may be numbered and 

 the labeled specimens referred to by means of cross-reference sheets 

 in the herbarium file. 



Specimens which are too small for convenient mounting on her- 

 barium sheets may be placed in small packets affixed to the sheet, 

 or, if very small and delicate, mounted whole on sUdes and then 

 cross-indexed. Inasmuch as the preparation of sUdes for study and 

 reference is of great importance in algology, it seems well to explain 

 here an easy method suitable for the majority of cases. 



Permanent slides may readily be made of most species and for 

 most general morphological purposes by using the ordinary crystal 

 clear variety of Karo corn syrup. Material preserved either in forma- 

 lin or alcohol may be prepared after washing in water. The specimen 

 is first stained either with anahn blue or acid fuchsin on a sUde by 

 adding a little aqueous stain, acidifying and then washing with a drop 

 or two of distilled water. After the excess water is drawn off with 

 blotting paper, Karo syrup, diluted to 50-60% with distilled water, is 

 appHed and the sHde left open to the air in a dust free place over 

 night. The next day, after the first drop of dilute Karo has dried down 

 so that excessive plasmolysis (shrinking) of the cells of the specimen 

 has been avoided, another drop of more concentrated Karo (about 

 80%) is added and the cover shp appUed to complete the preparation 

 which is self seaUng. The Karo dries around the edges within a few 

 days and although the sHde should not be allowed to stand on edge 

 for a considerably longer period, it may otherwise be handled with 

 ease. In the case of transections or of species with a dense structure 

 of small cells, plasmolysis is not appreciable, and these may be 

 mounted directly in 80% Karo. Very small bubbles usually will form 

 gradually under the cover sHp as the drying proceeds, but these rarely 

 affect the usefulness of the preparation. In the writer's experience 

 such slides have shown no appreciable deterioration after 15 years 

 of storage. 



For making sections of many specimens a freezing microtome will 

 prove most desirable, but in the absence of such an instrument good 

 sections can be made by hand with a razor blade after a Httle practice. 

 This is most easily accomphshed by using dried specimens, for in the 

 majority of cases such sections will expand in a drop of water to 

 very nearly their normal size and shape. If they do not, a httle heat 

 usually helps. Stubborn cases usually respond to the addition of 

 potassium hydroxide and heat. The most convenient cutting method 

 is that whereby the specimen fragment is held with a finger on a 



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