MEASURING PHOTOSYNTHETIC ACTIVITY 245 



ordinary form of the Haldane ^'"' apparatus. It is compact and can be 

 manipulated quite rapidly. The limits of accuracy are, however, such 

 that it does not serve where very small differences must be determined. 

 The apparatus has been somewhat simplified by Henderson.^' 



A gas analysis apparatus for carbon dioxide and oxygen which should 

 be of considerable value for experiments on photosynthesis has been re- 

 cently devised by Carpenter.^* It is based upon the Haldane principle, 

 but has a number of valuable refinements. It has a capacity of 40.04 cc. 

 In its present form it is somewhat limited in the per cent of carbon 

 dioxide which can be determined; gases containing up to 1.7 per cent of 

 carbon dioxide and from 78.4 to 79.6 per cent of nitrogen can be analyzed. 

 Readings can be made to 0.001 per cent. Naturally, in every apparatus 

 the measuring pipette must first be calibrated. In this apparatus oxygen 

 is absorbed by potassium pyrogallate and carbon dioxide by potassium 

 hydroxide.^^ 



An apparatus for gas analysis of a high order of precision has been 

 developed by Sonden.**' In this apparatus the two measuring pipettes, 

 the reagent reservoirs and the manometer, are connected by glass tubing 

 and glass stop-cocks so that the gas to be analyzed when once in the 

 apparatus does not. come in contact with any rubber connections. The 

 percentage of carbon dioxide that can be analyzed is limited to one per 

 cent. \Vith this apparatus undoubtedly results of a high degree of pre- 

 cision can be obtained. It is, however, rather difficult of manipulation 

 and transportation, quite fragile and can be repaired only by the most 

 expert glassblower. Recently Krogh *^ has devised an apparatus of great 

 accuracy though also of considerable complexity. 



Another apparatus *- for gas analysis which may be mentioned and 

 which permits the determination of higher percentages of carbon dioxide 

 is that of Polowzow-Richter. This has been used by the Russian school 

 of plant physiologists. The apparatus of Bonnier and Mangin is so well 

 known that it needs no comment.*^ The two forms of apparatus just 

 mentioned are especially suitable for the determination of the respiratory 

 and photosynthetic quotients. For determinations of this nature Maquenne 

 and Demoussy ** have also devised methods which are now well known. 



Warburg's Method. In his extended series of investigations on various 

 phases of the photosynthesis problem Warburg*^ has used a unicellular 

 green alga ChlorcUa. In order to determine the rate of gas interchange 



''Haldane, "Methods of Air Analysis," London, 2nd ed., 1918. 

 . '"Henderson, Jour. Biol. Chem.. 33, 31 (1918). 

 ''Carpenter, T. M., Jour. Metabolic Research, 4, 1 (1923). 

 "■'Benedict, Carnegie Inst, of Washington, Pub. 166, 75 (1912). 

 '"Sonden, Zeit. InstrumcntenJ^., 9, 472 (1889). 

 "Krogh, Biochemical Jour., 14, 267 (1920). 

 '-Richter, Trav. soc. imp. mt. St. Petersburg, 33, 311 (1902). 

 "Aubert, Rev. gen. Bot., 3, 97 (1891). Thoday, Ann. Bot., 27, 565 (1913). 

 " Maquenne and Demoussy, "Nouvelles recherches sur les echanges gazeux 

 des plantes vertes avec Tatmosphere," Paris, 1913. 

 *nVarburg, Biochem. Zeit., 100, 230 (1919). 



