99 



Also, we know nothing definite, at least nothing which holds good in 

 general, of the anatomical changes taking place when trees are planted too 

 deep. In some cases it has been observed that the ducts are filled with 

 brown, gum-like stifif masses, in others they are filled with tyloses accom- 

 panied by a brown discoloration of the walls. Gummy swellings of the mem- 

 branes are not infrequent. But these are all only occasional observations 

 and experimental study of the question is still needed. 



We will limit ourselves on this account to the enumeration of the dis- 

 coveries already made as to the influence of the two factors occurring most 

 generally when trees have been planted too deeply— the lack of oxygen and 

 the excess of carbon dioxid. We know that plants without a supply of oxy- 

 gen gradually die. If the living cell can take up no oxygen, it changes the 

 direction of its life-functions. Later it passes over into a state of rigidity, 

 since the phenomena of movement cease in the cytoplasm., the sensitiveness 

 to stimuli is lost and growth becomes inhibited. The plant, however, 

 does not die immediately. It continues to give off carbon dioxid for 

 some time and, with a renewal of the oxygen supply, it can even re-assume 

 its usual functions after a rather long apparent death. In this continuation 

 of life without oxygen (anaerobic) the oxygen necessary for the life pro- 

 cesses must be furnished from the substance of the plant itself and has been 

 called intra-molecular respiration. 



Lechartier and Bellamy^, in a series of experiments, have proved 

 that alcohol is formed in the parenchyma cells growing without a 

 supply of oxygen, not only in our pitted and other fruits, but also in the roots 

 and leaves. Stocklasa has also proved most recently tliat there is a forma- 

 tion of lactic acid. Even in fungi (Agaricns campestris), Muntz- found 

 alcohol and hydrogen in considerable quantities if the fungi were kept 

 for some time in air free from oxygen. The material for this alcohol can 

 have been furnished by the kind of sugar alone present here, named man- 

 riose, while in other fungi, producing only alcohol, (without hydrogen) in 

 an atmosphere of carbon dioxid, the trehalose must have been fermented. 

 If the fungus is not kept too long in the oxygen-free air, it can take up again 

 its normal life-functions, as has recently been proved by Krasnosselsky'' 

 for Mucor spinosa and Aspergillus .niger. Adolf Mayer* had earlier 

 expressed his opinion that fermentation produced by yeast, is a re- 

 sult of respiration in the absence of oxygen. Pasteur"' and Bohm" 

 had really proved already that all more highly organized land and water 

 plants behave in a very similar way, since, in media free from oxygen, they 



1 De la fermentation des pommes et des poires. Compt rond. t. I^XXIX, p. 949.— 

 De la fermentation des fruits ib. p. 1006. 



2 Comptes rend. KXXX I, p. 178. 



3 Krasnosselskv, Atmung- und Garung der Schimmelpilze etc. C'entralbl. f. 

 Bakteriologie etc., i904, Vol. XIII. Nos. 22-23. 



4 Mayer, A., Untersuchungen iiber die alkoholische Garung. Landwirtsch. Ver- 

 suchsstationen, 1871. 



5 Faits nouveaux pour servir a la connaissance de la th^orie des fermentations 

 proprement dites. Compt. rend. 1872, p. 784. 



6 Bohm, Ueber die Respiration von Landpflanzcn. Sitzungsbcr. d- k. Akad. d. 

 Wissensch. 67. Section I. 



