APPARATUS AND MATERIALS 53 



latter 5, 25, 100, 506 cc. capacity, kept in a rack over the sink), funnels (say 

 5, 8, 13, and 20 cm. diameter, kept in a rack over the sink). Glass stop-cocks. 

 Thermometers (two dozen of good grade chemical form, from o° to ioo°, 

 with at least one carefully standardized form for comparison). Glass tubing 

 (a full supply of all sizes, kept in drawers under the gas-table), especially 

 2 to 7 mm. inside diameter, with some barometer and some capillary. Sheets 

 of white glass (cleaned negatives are excellent). White saucers and plates. 

 Bottles of diverse forms and sizes. U tubes. Watch-crystals. Plain tum- 

 blers. Battery jars. Soyka flasks. Slides and covers. 



Other Supplies. Cork stoppers, many sizes. Rubber stoppers, espe- 

 cially 20 to 32 mm. diameter at large end. Rubber tubing, various sizes, 

 some black, some white (best bought fresh, as it spoils in time). Measures, 

 wooden metric, to serve as scales on tubes. Electrician's tape (one of the 

 most valuable materials of the laboratory, for making air-tight joints and 

 for many other uses). Tin-foil. Stop-cock grease. Sealing-wax. Copper 

 wire (sizes 16, 18, 20 are most useful; should preferably be on spools hung 

 over the tool-table). Beeswax. Artists' modelling-clay. Vaseline. Plaster 

 of Paris. Glue. Filter-paper. Cross-section paper (millimeter kind). 

 Gummed labels. Tracing-linen. Black paper, preferably white on one 

 side. Cheese-cloth. Pins. Strong thread. Porous flower-pots and saucers 

 of different sizes. Pulpwood saucers, pairs of four or five sizes (may be ob- 

 tained from dealers in gardeners' supplies). Supports and clamps of the 

 ordinary chemical sort. Sphagnum moss may be obtained, if no local supply 

 is available, from all dealers in gardeners' supplies. Blocks and wedges of 

 wood for supporting apparatus. Hard paraffin (in a water-bath saucepan, 

 always ready for safe heating). 



Chemicals. All in suitable, well-stoppered and well-labeled bottles. 

 Alcohol. Mercury. Formalin. Turpentine. Ammonia. The common 

 acids. Salt. And the others mentioned in the following pages. 



Seeds. These, of the much-used common kinds, Corn, Oats, Wheat, 

 Barley, Sunflower, String Bean, Horse Bean, Lima Bean, Morning-glory, 

 Garden Nasturtium, Squash, Castor Bean, Japanese Buckwheat, White 

 Mustard, Radish, Lupine, should be kept in suitable bottles on a shelf of 

 the chemical case. They should be obtained fresh each season from a reputa- 

 ble firm of seedsmen, the old stock being always thrown away just as soon as 

 the quality of the new has been proven. Poor seed can vitiate an experiment 

 to an extent unsurpassed by any other cause. 



Many of the furnishings, apparatus, and supplies of the physi- 

 ological laboratory, both those above described and others to 

 be mentioned in the following pages, are standard articles of 

 Physics and Chemistry, and can be bought from any dealers 

 in those supplies. But of firms making a specialty of supplies 

 for Plant Physiology, there are as yet but few, though there are 

 some. In Europe the various appliances devised by specialists, 



