CRUICKSHANK'S PRACTICAL TLANTER. 319 



clumps of park trees, which colonies of rooks or other 

 large birds frequent. 



Of the natural grass which Mr Cruickshank states 

 succeeds in woods to the original heaths, and which 

 he describes as affording such excellent tender food 

 for cattle, we can only say, that either the woods 

 must have been unprofitably thin, and the trees 

 naked, or that he has completely mistaken the qua- 

 lity of the herbage. The grass of woods is unheal- 

 thy food for cattle, and generally not relished, be- 

 ing rendered unpalatable and noxious by the resinous 

 and bitter droppings from the tree leaves, and by 

 the bitter and nauseous juices generated in the soil by 

 the roots of trees, which the herbage roots draw up. 

 In dry soils, there is sometimes an accumulation of 

 whitish substance within the ground, around the 

 roots of trees, which some refer to excrementitious 

 deposit but which, we think, is rather the produce 

 of a subterraneous vegetable, of the nature of a 

 fungus or mould. Wherever this has increased to 

 a considerable extent, we beheve old forest ground 

 will be found of great fertility. 



* It is a theory of Mr Sheriff, Mungo's Wells, that all plants 

 have excrementitious deposit from the roots, the deposit from one 

 kind affording a good manure to another kind. Thence the ad- 

 vantage of mixed grasses and legumes in pastures, and of the 

 rotation of different kimls of crops. 



