108 LABORATORY MANUAL OF GENERAL PHYSIOLOGY 



fluttering of valves. For description of gill see Comstock, "An Introduc- 

 tion to Entomology," 1920, pp. 319-320. 



6. Respiration in the Giant Water-Bug (Lethocerus). — Observe the air 

 tube at caudal extremity. Air is stored under the wing covers over the 

 tracheal openings (Comstock, p. 366). Sketch the animal at the surface. 



6. Respiration of Unicellular Organisms. — Place yeast suspension in the 

 Warburg-Barcroft (or other type of respirometer). Place a small roll of 

 filter paper soaked with 20% KOH in small vial to absorb CO2. Measure 

 the rate of O2 consumption (cf. Dixon, "Manometric Methods," 1934). 

 A differential volumeter is described by Fenn, Am. Instrument Co., 

 Washington, 1935. 



