METHODS OF RESEARCH: APPARATUS 81 



size and leave little to be desired. They are of polished oak 

 (about 10 feet high and with an internal diameter of approxi- 

 mately 4 by 4 feet). Specifications and blueprint drawings 

 may be had from the Bureau of Plant Industry, United States 

 Department of Agriculture. 



The equipment of the transfer room, which should have a 

 large window and a broad work-shelf on the side facing the best 

 light and several shelves at the right, consists of a cut-off gas- 

 burner, needles, loops, forceps, litmus paper, and various, mov- 

 able racks, tubes and dishes. There should be also a shallow 

 drawer under the work shelf for rubber bands, pencils for writ- 

 ing on glass, etc. 



Sub-cultures are placed for study at various temperatures. 

 These require closed cupboards for room temperatures, ice boxes 

 for temperatures from 15°C. to 0°C., electric or gas thermostats 

 for temperatures from 30°C. upward, and specially devised 

 ammonia apparatus for temperatures below 0°C. 



Thermostats. — Our thermostats are of various patterns. 

 Large sizes are preferable. The best one we have is an old in- 

 strument covered with felt, made many years ago by Rohrbeck 

 in Berlin. All our thermo-regulators are the French metal-bar 

 regulator commonly known as the Rovix. These require less 

 attention than those containing mercury or other fluids. 



Besides ordinary ice boxes we make large use of Paul Alt- 

 mann's ten-compartment ice thermostat, and during a part of 

 our year can keep the temperature in the lowest compartment 

 at 0.5°C., but not during the summer. 



Our stock cultures are carried in ordinary kitchen refrigera- 

 tors, but shelves in a specially cooled room would be much better. 

 Refrigerators that have the ice compartment over the storage 

 chamber are certain to leak into the latter sooner or later and to 

 spoil cultures. 



For thermal bath see "Bacteria in Relation to Plant Diseases," 

 Vol. I, Fig. 63. 



3. For Preparation and Study of Sections 



A paraffin embedding oven, microtomes, stains, staining 

 dishes, flawless slides and covers, good Canada balsam and 



