2 44 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



plots (3 and 4) with heavier liming the soil was loose and free 

 like mild humus. At the time when the photograph (Plate 

 XIV.) was taken the number and size of beech plants^were 

 as follows : — 



Plot I, no lime, 3 plants, average height 6| inches. 



„ 2, 2f cwts. lime, 3 „ ,, 10 „ 



5' 3> ^3\i )) 33 » >> ^3-j )> 



» 4, 68 „ 143 „ „ 22^ 



Other experiments, including one on a larger scale, have 

 confirmed the results just described. They also showed that 

 an excessive amount of lime may be injurious on these acid 

 humus soils, so that before beginning on a large scale it would 

 be well to test the requirements of any particular area by a 

 preliminary series of experiments. 



The effect of the lime in these cases is not due to its direct 

 action on the plant, but to its influence on the soil, and it is in 

 the study of this that P. E. Miiller has done much important 

 work. The studies were made in Denmark, but as is indicated 

 in the notes on woods, the general climate, soils and vegetation 

 of Denmark are sufficiently like those of Britain to allow of 

 useful comparison. 



The remains of plants and animals in drier soils, away from 

 marshes and bogs, are decomposed more or less completely and 

 converted into various sorts of humous soils. One of the 

 extreme types is " muld," mild humus or vegetable mould. 

 Another type is raw humus, acid humus or the Danish "mor." 

 These two types, " muld " and " mor " (using the Danish names), 

 show very different characters, but between the extremes there 

 exist all degrees of transitional soils. 



" ' Muld,' " in Dr Miiller's own words, "consists of the mineral 

 soil in intimate mixture with remains of plants and animals in 

 various degrees of decomposition. The mixing is carried on in 

 nature mainly by animals, especially earthworms. The organic 

 refuse is quickly decomposed (in woods, as a rule, in the course 

 of a year), and the decomposition is effected mainly by bacteria, 

 which by energetic fermentation of cellulose and sub-division of 

 the peptones rapidly brings the constituents of the refuse into 

 circulation again. The nitrogenous compounds are decomposed 

 with development of nitric acid. The natural ' muld ' soil has 

 a gritty structure and is loose, so that it is easily permeable by 



