﻿1903] CURRENT LITERATURE 227 



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Carefully washed leaves are extracted with equal parts of sterile distilled 



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water and c,p, glycerin. The extract may be used or the enzyme obtained 

 separately by shaking the extract with benzene, which is then decanted, 

 carrying with it the enzyme, which settles as a flocculent amorphous precipi- 

 tate. Other leaves, carefully washed, are dried at roo^ C, powdered in a 

 sterile glass mortar, and preserved in sterile glass with ground stopper. 

 From the powder also the enzyme may be extracted, as it bears a heat of 

 100° for some time. Repeated extraction, washing, and drying frees it 

 from the enzyme completely. The liquids to be tested were put into a 

 beaker, in which is plunged an inverted funnel, having inverted over its stem 



agraduated test tube filled with liquid, into which the gases rise as they are 

 set free. 



Repeated experiments show that the glycerin extract from the living leaves 

 or from the powder is unable alone to accomplish photosynthesis in light. On 

 the contrary, the powder alone, if it contain the enzyme, when put into dis- 

 tilled water always causes an evolution of oxygen, and at the same time pro- 

 duces formaldehyde, the presence of the latter being demonstrable by the 

 codein test. The enzyme is only able to produce photosynthesis in light 

 if chlorophyll be present, which, as Friedel thought, seems to act as a 

 sensitizer. The addition of an antiseptic, e. g., HgClo 1:2000,. does not 

 interfere with the process. CO2 is absorbed from the air by the liquid in 

 the beaker. The evolution of O is always proportional to the illumination. 

 The leaves do not alvva)^s yield the enzyme; they must be collected at a 

 proper season. ■ 



These results seem not only to demand a new point of view regarding the 



nature of photosynthesis, but to furnish a new and strong support to Baeyer's 



. hypothesis as to the process. At present the condensation of formaldehyde 



into a complex carbohydrate is not accounted for, nor do we know how a 



chemical sensitizer acts.— C. R. B. 



The PATH BROKEN by Jacobi (Flora 86: 289-327. 1899) has been explored 

 much farther by Treboux,^5 ^ho agrees that even dilute doses of the stronger 

 metallic poisons hinder photosynthesis in Elodea. Anesthetics and alka- 

 loids act in the same way. Milder poisons such as KNO3 exercise no very 

 considerable influence until concentrated enough to plasmolyze the cell, when 

 they permanently injure it. Acids, including carbonic acid, accelerate the 

 evolution of oxygen in proportion to their concentration (within Hmits, of 

 course). No evidence could be found for the formation of starch from formal- 

 dehyde, nor for any place for formaldehyde in photosynthesis. The Elodea 

 used for these experiments, conducted in Leipzig, seems to have been a great 

 deal more sensitive than the Chicago material (cf. the February number of 



the Gazette, p. 96).— E. B. Copelaxd. 



'STreboux, O., Einige stofHiche Einfliisse auf die KohlensHureassimilation bei 

 submersen Pflanzen. Flora 92 149-76. 1903. 



