2J4 DISEASES OF TREES 



impossible. In the case of peeled stems that are freely exposed, 

 drought in a few weeks induces the formation of cracks in the 

 alburnum. These occur about an inch apart, and penetrate to a 

 depth of an inch or more. The rain-water enters these cracks, 

 carrying with it any spores that it may contain. After pro- 

 longed rain the wood swells owing to the absorption of water, 

 and the cracks close. During wet years, or long storage of 

 the timber, decomposition may begin even in the forest, the 

 spores that have entered by the cracks germinating and causing 

 the wood to become brown along both sides of the fissure. 



As a rule, however, spores that enter cracks in the alburnum 

 do not germinate in the forest, because when the rain ceases the 

 superficial layers of the wood quickly dry again, so that even if the 

 cracks should have closed they subsequently reopen. Should such 

 wood be removed from the forest to the building or saw-mill in 

 a dry condition, it remains sound, even although the spores in 

 the cracks retain their power of germinating for a long time- 

 If, on the other hand, the wood is floated, so that it has the 

 opportunity to become again fully saturated with water, a very 

 undesirable pathological symptom makes its appearance, which 

 is known to saw-millers, timber-merchants, &c., as " the red 

 stripe," and represents the first stage of what is popularly called 

 dry-rot." 



It is a familiar fact that there is no essential difference as 

 regards durability, or resistance to the attack of M. lacryinans 

 and other wood-fungi, between coniferous timber that is felled in 

 summer and that which is felled in winter. The attempt that 

 has been made to show that the destructive effects of M. 

 lacrymans are modified by the varying chemical composition 

 (as regards potash, phosphoric acid, &c.) of wood felled in 

 summer and in winter must be described as total failures. On 

 the other hand, it is an undoubted fact that wood which is felled 

 in summer suffers far more from dry-rot than that which is felled 

 in winter. This apparent contradiction is easily explained. 

 Winter-felling takes place in the lowlands and in the less 

 elevated mountains. In these districts the timber is chiefly 

 removed from the forest by land, after it has lain for a longer or 

 shorter period with or without its bark. Such timber is either 

 free from spores, or, should it contain spores that have entered 



