52 PLANT PHYSIOLOGY 



door, while it is otherwise convenient and very neat in appearance. It does 

 not, however, keep very constant in temperature. Of course any water- 

 bath, even a beaker standing in a dish of warmed water, may be made to 

 serve as a drying-oven. 



Gas-generators. Those most needed are for carbon dioxide and for 

 hydrogen. I like best the Kipp's automatic form, capacity i quart, sold 

 by all supply companies. They are most convenient when kept, with their 

 wash-bottles, upon a tray provided with handles, permitting their ready 

 transport. If carbon dioxide in large quantities were needed, it would be 

 better to use the commercial compressed gas now everywhere obtainable, 

 and even the omnipresent seltzer bottle can be used at a pinch. Simple and 

 efficient, though rather wasteful, generators can be adapted from common 

 bottles with stoppers bored for an outlet tube, and for a thistle-tube through 

 which the acid is poured in. But a much more economical form can be 

 constructed from common laboratory materials exactly upon the Kipp's 

 principle. The stopper of a wide-mouthed bottle is bored to take an outlet 

 tube and the large end of a calcium-chloride tube, the bulb of which hangs 

 near the bottom of the bottle, the whole arrangement being made tight by 

 hard paraffin. The marble or zinc rests upon a paraffin disc attached to 

 the calcium-chloride tube just below the bulb. When not in use the outlet 

 is closed and the accumulating gas forces the acid into the calcium-chloride 

 tube, which is loosely stoppered. 



In addition to these larger, and more or less permanent, 

 laboratory furnishings, there are many equally indispensable 

 smaller articles which are not only needed for the daily manipu- 

 lation of the laboratory, but are also desirable in anticipation 

 of that constant trial for new and better methods, and of those 

 special studies and investigations which ought constantly to be 

 in progress. These are, of course, aside from the special appli- 

 ances for particular experiments, all of which will be described 

 in the appropriate places in Part II. The general appliances 

 are the following: 



Tools. Files, round and triangular, three or four sizes of each, and a 

 large, flat one. Pliers, combined wire-cutting and twisting. Spirit-levels, 

 small, including one circular. Soldering outfit. Carpenter's hammer, 

 square, dividers, fine saw — in fact a small case of the standard tools of good 

 quality. Small metal-working set. Vernier calipers. Whetstone. Scissors 

 and shears. Set of cork -borers, and cork-presser. Small pruning shears. 



Glassware. Bell jars, in pairs (for control experiments) of the different 

 sizes, and several pairs of a standard size, preferably with ground neck and 

 stopper and ground base; and ground-glass plates for the same. Also the 

 standard forms of beakers, test-tubes, crystallizing dishes, conical flasks, 

 thistle-tubes, wash-bottles, Petri dishes, burettes, cylindrical graduates (these 



