102 EXPEiaMi:NT station record. 



ill :\ liours. The claiin tliat tlie (lecoini)().sition in the light is the result 

 of partial oxidation the author tbuiul to 1)6 correct, tlie acidity of 

 .O.t;((Iis i»hiuts kept for 1 hours iu air, in hydroj^eu, aud in darkness, 

 being respectively 813, S82, aud 903. 



The decomposition of organic acids at high temperatures, :>') to 40'^ 

 C, is common. This is shown by subjecting parts of plants that have 

 already lost i)art of their acidity to higher temperatures, when the 

 decomposition continues. 



When plants are taken fioin the snuliglit into darkness and kept at 

 the room temperature for a cousideiiible time, an increased activity 

 of acid formation takes place, followed later by decomposition. This 

 period varies for different plants, being 8 hours for Crassulaeew and 24 

 hours for Rohiiiia, with O.ralis and rdan/onium intermediate. This 

 difference the author thinks may be due to the different kinds of acids 

 contained in the plants. 



In common with others the author thinks the decomposition of 

 organic acids is a process which all i)lants have in common. It is pro- 

 moted by sunlight and higli temperature, and may be temporarily 

 checked by the opposing process of acid formation by changing ]»lants 

 from sunlight to darkness. 



The production of organic acids takes place when a plant is kept in 

 the dark at ordinary temperature, but after several hours in darkness 

 decomposition will take the place of construction. The influence of 

 temperature on acid production was investigated, and a temperature 

 of 12 to 1~P C found to be best. 



The influence of oxygen was tested in an atmosphere of hydrogen. 

 It was shown that oxygen is more important to acid formation than to 

 its decomposition. 



The author thinks there is a close relation between the production 

 and decomposition of the organic acids and the character of the gas 

 exchange taking place iu the dark. A similar relationship is shown in 

 the case of a high temperature as well as in darkness. With the 

 increase of the acid decomposition the ratio between the oxygen and 

 carbon dioxid of respiration, or the respiration quotient, as the author 

 calls it, begins to increase and continues to do so for several days. An 

 experiment with Sedum hyhridum showed, at the time of placing the 

 plant in the dark, for its respiration quotient 0.44, 2 days later 0.7, and 

 after 3 days more 1.05, while the acidity of the plant had fallen from 

 3G0 to 300. With germinating seeds the respiration ipiotieut- first falls 

 and then rises, while the degree of acidity reaches its maximum at the- 

 minimum period of respiration. 



The author thinks that all things tend to prove that organic acids 

 in plants are the result of imperfect oxidation of the carbohydrates 

 and not by-products of albuminoid synthesis. The decomposition of the 

 acids often depends on their change by oxidation to carbon dioxid. 

 This may not take place all at once, but gradually by progressive steps 



