Ailanthus trees of the Ring^strasse in \'ienna wliich liad been planted too 

 deep. These trees years before had fallen olT in growth, for in the first year 

 after they were planted, their annual rings were more than 3 cm. broad, in 

 the last year the growth was 0.5 cm. At the time of death the earth about 

 the roots was found to be so injurious that seeds of different plants sown in 

 the soil in the open and under bell jars began to decompose at once. Seeds 

 developed luxuriantly, however, after this soil, repeatedly washed with 

 water, had been exposed in thin layers to the atmosphere for eight warm 

 days in July. Similar experiments were undertaken by Mangin^ w^ho, 

 before this time, had ascribed the diseased appearance of the street trees in 

 Paris to the bad composition of the soil. Seeds and tubers sown in soil re- 

 moved from around diseased roots showed an interrupted development. 



The air tests made near the diseased roots of Ailanthus showed a de- 

 ficiency of oxygen and a preponderance of carbon dioxid and Mangin- 

 suspects that the lack of oxygen may be traced back to a reduction by 

 sulfids. Certainly numerous micro-organisms co-operate in the decom- 

 posing process of the roots. However, such an attack by the suitable 

 bacteria would not have taken place if the oxygen in the soil had not begun 

 to be deficient. 



When trees with spongy bark have been planted too deep, as in the 

 above mentioned Ailanthus trees in Vienna, the bark under the soil is found 

 entirely rotted away. According to the age and the bark structure of the 

 tree, as well as the physical constitution of the soil, a disturbance of the ab- 

 solutely necessary circulaticni of the air will appear sooner or later in the 

 buried base of the trunk. This disturbance wdll be felt also in both the ven- 

 tilatory systems of the trunk, viz., in the vascular system of the wood body 

 and the bark system communicating with it by means of small hollow spaces. 

 The green bark parenchyma protected by the more or less strongly developed 

 cork is bathed by the atmospheric air; it penetrates through the lenticels 

 into the intercellular spaces where it circulates. The air penetrates the ducts 

 of the wood, partly through the water from the roots, but largely by diffu- 

 sion from the sides and is also in circulation, as mentioned above. In fact, 

 as may be assumed from the investigations, of O. HohneP, a daily 

 periodicity probably takes place in this circulation. The ducts originally 

 hlled with w^ater are partly or entirely emptied in the course of the day, 

 since the superior and surrounding tissues draw away the water. The trans- 

 piring leaf body of the tree needs a very large amount of water and draws 

 it from the wood tissues of the branches which make good their losses from 

 the trunk, in w'hich therefore a suction wave advances down toward the 

 base and thence out into the roots. 



1 Mangin, L., Sur la vegetation dans line Atmosphere viciee par la respiration. 

 C. rend. 1896, p. 747. 



- Mangin, L.., Sur I'sieration du sol dans les promenades et plantations de Paris, 

 C. rend. 1895, II, p. 1065. 



a V. Hohncl, Beitrage zur Luft- und Saftbewegung in der Pflanze. Pringsh. Jahrb. 

 f. wissensch. Bot. Vol. XII, Part I, p. 120. 



