58 AERATION AND AIR-CONTENT. 



live under the new conditions in a manner similar to that of ferments. 

 He found that when fruit is placed in an atmosphere of CO 2 , respira- 

 tion proceeds in consequence of the decomposition of sugar. The 

 cells are in the condition of ferments which live without free oxygen, 

 as in the case of cells of Mycoderma vim when submerged. In fact, 

 as soon as the fruit is placed in C0 2 , both carbon dioxid and alcohol 

 are produced in small amounts, while the fruits remain firm and 

 entirely sound in appearance. 



Lechartier and Bellamy (1869; 1872; 1874) determined that C0 2 and 

 alcohol were formed when fruits were kept in a closed receptacle 

 without oxygen, though it was impossible to find an alcoholic fer- 

 ment in them. Further study of the respiration of fruits showed that 

 cherries, gooseberries, figs, and lemons, as well as beets and potatoes, 

 and the leaves of cherry, gooseberry, etc., behaved as did pears and 

 apples in the earlier experiments. They concluded that life does 

 not stop in the cells of a fruit or leaf as soon as detached from the 

 plant. Activity continues under the exclusion of the air through the 

 consumption of sugar and with the production of alcohol and C0 2 . 

 The moment at which the production of C0 2 ceases is at the final 

 death of the cell. As a consequence, fruits, seeds, and leaves can 

 remain inert indefinitely if micro-organisms do not develop in them. 



Deherain and Moissan (1874 : 356) found that leaves placed in 

 an atmosphere deprived of oxygen continued to evolve C0 2 for 

 several hours, the evolution apparently ceasing only when all the 

 cells were dead. The resistance to death in the absence of oxygen 

 varied greatly from one species to another. They also showed that 

 CO 2 produced a slowing down of respiration, while Borodin (1875) 

 obtained similar results in contrast to the behavior in an atmosphere 

 of hydrogen. Deherain and Vesque (1876 : 327) studied the ab- 

 sorption of oxygen and the emission of carbon dioxid by roots, in 

 extension of the work of Saussure. In addition to confirming the 

 normal behavior of roots in air, they placed them in pure oxygen, 

 and also in air deprived of oxygen. The former gave no bad effects 

 in the case of Veronica. Plants of the latter lived for 7 days in an 

 atmosphere of nitrogen, and those of ivy for 15 days, but finally the 

 leaves fell and the plants died. Plants of ivy placed in an atmosphere 

 of pure carbon dioxid died speedily, the leaves drying up and the 

 vegetative point falling away. They also showed (1877 : 959) that 

 a feeble excretion of carbon dioxid occurs when oxygen is absorbed 

 by the root. Plants did not seem to suffer by the substitution of 

 oxygen for the air in the soil about the roots, but the emission of 

 CO 2 was somewhat greater. When small amounts of C0 2 were 

 added to the soil-air or to oxygen, the plant did not appear to suffer, 

 but it died if kept in pure CO 2 . It also died when the roots were 

 kept in an atmosphere of nitrogen, but the action was much less 

 rapid. 



