WOUNDS 237 



injury is due to the separation of the cortex during the season 

 of cambium-activity, and provided the cambium can be preserved 

 against drought by the immediate application of a bandage, 

 which, however, must not come into contact with the cambium. 

 The only practicable means consists in binding moist oil-cloth, 

 straw ropes, moss, or such like round the stem. 



Should there be no prospect of a new cortex forming, every- 

 thing should be done to favour the production of a callus. All 

 dead and crushed portions of cortex which may press in- 

 juriously on the edge of the wound should be removed with a 

 sharp knife, only those portions of cortex which remain uninjured 

 on the surface of the wound, and which are nourished through a 

 connection with the edge, should be carefully retained. From 

 these a callus is formed quite as quickly as from the edge of 

 the wound proper. 



In order further to guard against wound-diseases, all loose 

 portions of cortex along the edge of the wound should be 

 removed, as moisture lingers for a long time between them and 

 the wood, and is absorbed by the latter. The moisture itself 

 hastens decay in the wound, and moreover it induces condi- 

 tions that are favourable for the germination of the spores of 

 infectious fungi, which thus gain an entrance into the interior 

 of the tree. 



In the case of those conifers which are supplied with resin- 

 ducts, wounds need be protected only when a thick branch which 

 possesses duramen is cut or broken off, or when the cortex 

 has become detached by pruning or the barking of game during 

 summer. The spruce is most exposed to wounds of this 

 character. 



The wounds of dicotyledonous trees require protection at all 

 seasons. In order to form a waterproof covering over the wound, 

 grafting-wax is used by gardeners and coal-tar by foresters. 

 I have never observed any injurious effect of the tar on the 

 tissues, as has been repeatedly asserted by practical men ; in 

 fact, I can affirm that it is only the ruptured organs and their 

 walls that are penetrated and impregnated by the tar. Cells in 

 the immediate neighbourhood of vessels, and libriform fibres that 

 were filled with tar, remained healthy and perfectly sound after a 

 number of years. 



