160 STATE HORTICULTURAL. SOCIETY. 



always adapted to some special end, and we should naturally infer that, 

 since nature always does her best to heal wounds, it must be because the 

 plant would otherwise suffer. Experience certainly shows that open 

 wounds are dangerous in plants as they are in animals, although I would 

 not go so far as to say that they are inevitably dangerous. There is no 

 doubt, however, that in most cases they are dangerous. Every surgeon 

 recognizes the dangers attending open wounds in animals, and, before the 

 days of the antiseptic treatment, the dangerous and often fatal results of 

 operations were due in many cases to the entrance of germs from the air 

 into the system through open wounds. In the same way wounds of plants 

 are dangerous, although a fatal result may not be reached before the expira- 

 tion of several years. Naturally the intact epidermis of the younger 

 parts of plants and the corky bark of the older branches and trunks 

 prevent the access of the spores and mycelium of fungus parasites to the 

 more sensitive tissues beneath. Where the bark has been removed, they 

 may and often do work their way into the interior, and cause, at first, a 

 local and, later on, a general decay of the trunk. The fungi which are the 

 agents of destruction in such cases are not the rots, smuts, or mildews, 

 which affect rather herbaceous plants than trees, but fungi of the toadstool 

 family. Those of you who have watched the larger wounds of trees must 

 have often seen clusters of toadstools of different kinds growing out of the 

 wounds. They are most frequently seen in the warmer months, but there 

 are a few species which are to be found even in the mild weeks which 

 sometimes come in midwinter. Besides the fleshy toadstools there are 

 many species of punk-fungi, belonging technically to the same family as 

 the toadstools, which infest wounds, and they are so tough and hard that 

 they can be found throughout the year. 



The question might arise whether these toadstools and punk-fungi grow 

 in wounds because the exposed wood is already dead and therefore furnishes 

 food for the fungi, or whether, on the other hand, the death and decay of 

 the wood are brought about by the presence of the fungi. In a certain 

 sense both these questions may be answered in the affirmative. When the 

 exposed wood dies, it furnishes a soil in which the spores of the toadstools 

 and punk-fungi can germinate and grow, and it is also true that when 

 they have once begun to grow, many species are able to make their way 

 downward and upward into the healthy parts of the branches and cause 

 them to rot. It is a very common experience that the rotting which began 

 in a wound gradually extends to the main trunk, so that although the 

 bark, except where the wound exists, appears to be perfectly sound, on cut- 

 ting the tree down, the whole trunk is found to be rotten or hollow. 



What happens, except in very small wounds which heal at once, is as 

 follows: The porous wood takes up moisture from the air in greater or 

 less amount according to the season, but in almost all cases enough to cause 

 the outer exposed part to decay in the course of from a few weeks to a few 

 months. Not only is water absorbed from rains and mists but dust and 

 other organic substances gradually collect on the surface and there is thus 

 formed a sort of soil, in a thin layer to be sure, but enough to support at 

 first the growth of bacteria, which help on the decay of the solid parts, 

 and, later, offer a^ favorable field for the germination of the spores of toad- 

 stools. A very small amount of damp soil is sufficient to start the growth 

 of these toadstool-fungi. Their spores, when they germinate, give out a 

 series of branching threads, the mycelium. The threads gain strength as 

 they grow, and, in a good many species, they at length acquire the power 



