32 A MANUAL OP THE CONIFER*. 



li m p,, " chalybeate " waters, iron, " hepatic " waters, sulphurated hydro- 

 gen, &c. * 



Stagnation of water at the roots induces disease by the " growing 

 points " of the spongelets being too much stimulated into growth in 

 the low temperature at which water-logged soil is always found, t 

 The roots exposed to the action of the water soon become debilitated 

 and unable to perforin their functions, they die and rot; fungus 

 (Polyphorus) is generated, which soon spreads over the living as well 

 as the dead parts, and the plant perishes. 



The destructive action of smoke is seen in the sooty particles that 

 -settle on the foliage and bark of the branches. The stomata of 

 the leaves and the pores of the bark of the young shoots are thus 

 choked, and the functions of these organs permanently injured ; the 

 foliage falls off before its usual term of persistency is complete, and 

 the plants have that denuded unsightly appearance so commonly seen 

 in the immediate vicinity of London and other large towns. 



Wounds and the mutilation of young Coniferous trees during the 

 season of active growth often causes their death, through an excessive 

 flow of the sap. "The sap like the blood oozes out or escapes at 

 the newly-made wound; its passage is a mute protest against our 

 violence, and whispers to the wise operator as it flows, to make as 

 few wounds as possible. All the sap that thus exudes is lost, it 

 represents so much waste of vital energy. But in the case of Conifers 

 it does more than this, the wounds are apt to become festering sores, 

 they attract towards them the secretions of the plant, to be not 

 simply discharged and lost, but to form centres of incurable disease, 

 ending often in running sores and life-long exudations of gummy 

 and resinous matter." J A remarkable instance of wounding was once 

 brought under our notice. A man while mowing had cut round the 

 stem of a large Araucaria imbricata in vigorous growth with his scythe • 

 the flow of sap from the wound was so incessant, that the tree bled 

 to death in spite of all efforts to stop it. It is evident, therefore 

 that the pruning of Coniferous trees, especially those belonging to the 

 Fir and Pine tribe in which the circulation of the sap is exceedingly 

 active, cannot be too strongly deprecated. If practised at all, it should 

 be restricted to the cutting or heading back of the fewest shoots 

 possible, and this should be performed in winter when the risk is least. 

 It is the want of an adequate compensating power in the Fir and 

 Pine tribe to repair injuries, that renders it not only injudicious but 

 even dangerous to amputate branches in vigorous health at any season. 



* See Chemistry by Professor Williamson, p. 619. 



t Dr. Lindley observes :-<' Watei r is not of itself an evil; on the contrary, it is the 

 food of plants, and its absence is attended with fatal results. It is the excess of wa£r 

 Irolueidtu™ 137' JUSt aS m 6XCeSS ° f f0 ° d iDJUreS mimah -"-Tteorij and Practice of 



J Gardeners' Chronicle, 1868, p. 761. 



