reduce a part of their substance by fermentation to carbon dioxid and alco- 

 hol, as do the yeasts in self-fermentation. The green parts of plants at any 

 rate, with sufficiently intensive illumination, can establish an atmosphere 

 suited to their normal respiration by decomposing the carbon dioxid which 

 had been given oflf immediately before. Aerobic and anaerobic respiration are 

 interdependent and anaerobic is able to withstand total destruction for some 

 time, even if growth is impossible This retardation becomes greater as the 

 temperature is lower. Thus, for example, Pfefifer^ cites the observations of 

 Chudiakow, that the failure of the carbon dioxid production, i. e. the pos- 

 .'^^ibility of living, begins after twelve hours in seedlings of maize at a temper- 

 ature of 40°C., after 24 hours at i8°C. and only after some days at a lower 

 temperature. If an organism or one of its members always has a lower 

 vitality, it also will keep alive longer in a place free from oxygen. Thus, 

 under such conditions, apples and pears at a moderate temperature have 

 been kept growing and ripening for months while rapidly growing moulds 

 and aerobic bacteria went to pieces quickly. In seedlings of phanerogamic 

 plants (Vicia Faha, Ricinus etc) there is an increase in the intra-molecular 

 exchange, 



Stich's- experiments show that single plants at times, or parts of 

 plants, at first exert no influence on the oxygen content in the air by their 

 respiration since, in a hydrogen atmosphere, they form exactly as much car- 

 bon dioxid as in air. With 8 per cent, of oxygen in the air, the respiratory 

 quotient was still normal, — with a lesser content (2 to 4 per cent.) it was 

 changed in favor of carbon dioxid because an intra-molecular respiration 

 took place. When the plants were kept for a longer time in an atmosphere 

 poor in oxygen, the normal respiratory quotient was gradually produced to- 

 gether with a decrease of the absolute amount of oxygen and carbon 

 dioxid. In a gradual withdrawal of the oxygen, the intra-molecular 

 respiration is first stimulated by a considerably lower percentage of oxygen 

 than when the oxygen diminution is sudden. 



Brefeld's-^ experiments lead to the conclusion that alcoholic fer- 

 mentation in all plants, from the lowest to the highest, takes place as soon 

 as the oxygen supply ceases. A very essential difference is shown, however, 

 in the different organisms which produce alcohol. While generally in yeast 

 (Saccharomycetes) the phenomenon of fermentation is to be considered the 

 climax of the normal activity of the organisms (which actually grow during 

 the process of sugar decomposition), it appears in the cells of phanerogams 

 as an abnormal process ending prematurely in the death of the cell. This 

 differs essentially from the pure fermentation of yeast producing only alcohol 

 and carbon dioxid, by the appearance of further products of decomposition 

 among which fusel oil and acids are especially noticeable. There is a great 



1 Pfeffer, Pflanzenphysiologie, 1897. Vol. I, p. 544. 



2 Stich, C., Die Atmungr der Pflanzen bei verminderter Sauerstoffspannung und 

 bei Verletzuneren. Flora ISni, p. 1. 



3 lUeber Garung- III, Vorkommen und Verbreitung der Alkoholgarung im Pflan- 

 zenreiche. Bot. Zeit. 1876, p. 381. 



