CHAP. XLIX HIGH-MOOR FORMATION 201 



poor in lime. The peat formed is poor in assimilable nitrogen, potassium, 

 phosphorus, and consequently in the most important nutrient bodies 

 belonging to soil. According to most authorities lime in the soil opposes 

 the production of high-moor because Sphagnum so it is reputed is 

 calciphobous. But Grabner's 1 opinion is that Sphagnum cannot endure 

 a concentrated solution of salts, whatever be the nature of these, and can 

 only grow where very little nutrient matter is contained in the water. 

 Weber, 2 as well as Transeau, 3 on the contrary, regard the amount of 

 nutrient salts in solution as being only of subordinate significance. 



In regard to the production of high-moor the important work by 

 Friih and Schroter 4 should be consulted. 



ADAPTATIONS AND FLORA 



Sphagnum and its growth. The construction, conditions of life, 

 and mode of growth of Sphagnum, cause the peculiar type of vegetation 

 of this moor. The smooth stem is densely beset with leaves and emits 

 a branch at each fourth leaf ; in many species the branches are pen- 

 dent and apply themselves more or less closely to the stem. At its 

 periphery the stem shows 1-5 layers of large, thin-walled, hyaline, capil- 

 lary cells, whose walls are often strengthened by tracheidal thickenings 

 and contain pores. By this means and by the dense growth of the 

 moss there are formed capillaries, which eagerly suck in water and 

 hold it firmly. It is erroneous to suppose that Sphagnum sucks up 

 water from the soil ; it raises water only for an inconsiderable distance. 

 The movement of water in a Sphagnum-moor is essentially a descend- 

 ing one. 5 The depth at which the water-table lies is dependent 

 upon the atmospheric precipitation and upon the permeability of the 

 peat and of the substratum. The leaf consists of a single layer of 

 cells ; some of these are narrow, long, and green, and together form 

 a network, whose meshes are occupied by larger cells which, being 

 colourless, perforated, and like the capillary cells of the stem, act in 

 the same manner as these. The result is that where moisture is present 

 the Sphagnum-plants are laden from top to bottom with capillary water. 

 As the older parts die off and are converted into peat, 6 the apices constantly 

 and vigorously elongate ; thus one generation is founded upon another. 

 In this way the Sphagnum-moor continues to grow in height, surface, 

 and periphery, so long as the rainfall and the dew suffices : desiccating 

 wind is directly hostile to this type of vegetation. In this manner 

 there arise thick, soft masses of moss, which raise themselves to a con- 

 siderable height, often bulging upwards more at the centre than at the 

 periphery, because the water in the centre has had the most prolonged 

 access. Hence the name 'high-moor'. When once a high-moor is estab- 

 lished it constantly extends at its edges and invades areas hitherto 

 intact. Sometimes Sphagnum-clothed tracts, kilometres in width, sur- 

 round the convex margin of a high-moor and may increasingly convert 

 more and more of the adjoining forest into bog. The forest is thus 

 gradually exterminated. 



1 Grabner, 1895. * Weber, 1900. 3 Transeau, 1905. 



* Fruh und Schroter, 1904. * Weber, 1902. 



6 Concerning the power of this to raise water, see p. 61. 



