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Corks should be selected from the best stock, should be as compact as possible, and should be without cracks or other defects. In form they should be cylindrical, so as to make a good joint with the sides of the tube. The ends must be flat, with clean cut edges, so that no fragments can get into the alcohol. With large tubes it is desirable to put a plug of cotton inside the tube next to the cork, since the alcohol extracts the tannic acid from the cork and is stained brown thereby.
To preserve small, delicate animals, such as eggs and larvie, it is well to place the small tube containing the objects in alcohol, closed with a cotton plug, inside a larger vessel, which is likewise filled with alcohol. This p,rraugement prevents danger from evaporation and minimizes the liability to breakage. One must see, however, that the cotton contains no acids and does not stain the alcohol. Absorbent cotton is the most suitable, of course, but the best quality of ordinary cotton will answer every purpose.
For large, flat objects, such as Asterids, Pleuronectids, and the like, rectangular jars with flat sides are recommended. These jars are made to be closed with a plate of glass, cemented on. Gutta-percha cement is generally used. Such receptacles have the great advantage that they do not distort the view of the object within them. For delicate forms, which are long and stiff, like Funiculina glass tubing of proper size, cut off at the right length, is used, one end being closed in the Bunsen flame and the other with a cork.
For preliminary manipulations much use is made of glass crystallizing dishes with flat bases and perpendiular sides, in which many specimens can be placed in little liquid without touching or interfering with one another. They are especially advantageous for keeping animals alive in sea water, letting them remain at rest until thoroughly distended; for killing by different methods, either slowly or quickly, and for hardening objects in different solutions until they are transferred to permanent receptacles. These crystallizing dishes have ground edges so that they may be tightly covered with disks of glass, when desirable. For hardening worms and other elongated animals use may be made of long rectangular vessels covered with a sheet of glass, or of the zinc trays to be described later.
It is also necessary to have a number of ordinary beakers (or battery jars) of diiferent sizes, which serve for the preserving of animals alive, tubes for the reception of small animals, pipettes for the extraction of minute forms from jars of water, glass rods, reagent bottles, graduated cylinders, etc.
For preserving animals, especially fish, of a size too great for such glass receptacles as have been mentioned, a rectangular case or box of zinc with a shallow trough around the margin is very useful. The cover, likewise of zinc, has its edge made to fit into the trough. To prevent evaporation the trough may be filled with water and a layer of oil. The cover has an opening in the middle to permit the escape of the air which is compressed under it by closing the box. This opening is provided with a cork. It must be acknowledged that these boxes have the disadvantage that, after a time, the zinc becomes corroded, probably by some acid formed in the alcohol through the action of dead animal matter. It is a good plan to protect the metal box by an exterior wooden case. In place of the rectangular vessels of glass for hardening animals of elongated form, the station uses some made of zinc with a layer of waxin the bottom. The wax bottom is for the purpose of holding the wooden pins used in straightening out worms while they are hardening. Pins of orange or other hard wood are preferable to those of metal, because the fixing fluids attack metals. A convenient size for such a tray is 60 by 6 by 6 cm. with about 1 cm. of wax in the bottom.
For the transfer of objects from one receptacle to another spatulas are largely used. These are made preferably of horn, because that material is not attacked by the reagents in use. They range in size from 6 mm. (one-fourth inch) to 10 cm. (4 inches) in width, and are of a convenient length, say 17.5 to 20 cm. (7 or 8 inches).
A pair of soft iron forceps 30 cm. (12 inches) long is very convenient for taking objects out of deep receptacles. Iron is both cheaper and just as good as brass for that purpose. Small forceps, wire cutters, syringes, and so on are used at times.
The apparatus for narcotizing certain Actinians is constructed as follows: The nose of a pair of bellows is provided with a metallic bowl which fits over the metal bowl of a tobacco pipe. The latter is provided with a peg which fits into a slot in the bowl on the bellows and fastens the two together. The tube of the tobacco pipe is continued with a piece of flexible rubber tubing which terminates in a U-shaped piece of glass tubing, the distal end of which has been drawn out to a point. With this apparatus one can easily force smoke into a receptacle