278 



NATURE 



[Jan. 19, I 



The structure of the walls of the tracheide^ and cells of 

 the wood is completely destroyed as the fungus hyphse 

 extract the minerals, cellulose, and other substances from 

 them. The minerals are absorbed at points of contact 

 between the hyphee and the walls, reminding us of the 

 action of roots on a mirble plate : the coniferin and other 

 organic substances are no doubt first rendered soluble by a 

 ferment, and then absorbed by the hyphas. This e^creUon 

 of ferment has nothing to do with -the excretion of water 

 in the liquid state, which gives the fungus its specific name : 

 the "tears" themselves have no solvent a:tion on wood. 



It will be evident from what has been stated that the 

 practical application of botanical knowledge is here not 

 only possible, but much easier than is the case in dealing 

 with many other diseases. 



It must first be borne in mind that this fungus spreads, 

 like so many others, by means of both spores and my- 

 celium : it is easy to see strands of mycelium pissing 

 from badly-diseased planks or beams, &c., across inter- 

 vening brick-work or soil, and on to sound timber, which 

 it then infects. The spores are developed in countless 

 myriads from the fructifications described, and they are 

 extremely minute and light : it has been proved that they 

 can be carried from house to house on the clothes and 

 tools, &c., of workmen, who in their ignorance of the 

 facts are perfectly careless about laying their coats, imple- 

 nients, &c., on piles of the diseased timber intended for 

 removal. Again, in replacing beams, &c , attacked with 

 dry-rot, with sound timber, the utmost ignorance and 

 carelessness are shown : broken pieces of the diseased 

 timber are left about, whether with spores on or not ; and 

 I have myself seen quite lately sound planks laid close 

 upon and nailed to planks attacked with the "rot." 

 Hartig proved that the spores can be carried from the 

 wood of one building to that of another by means of the 

 saws of v.'orkmen. 



But perhaps the most reckless of all practices is the usage 

 of partially diseased timber for other constructive purposes, 

 and stacking it meanwhile in a yard or outbuilding in the 

 neighbourhood of fresh-cut, unseasoned timber. It is 

 obvious that the diseased timber should be removed as 

 quickly as possible, and burnt at once : if used as firewood 

 in the ordinary way, it is at the risk of those concerned. 

 Of course the great danger consists in the presence of 

 many ripe spores, and their being scattered on timber 

 which is under proper conditions for their germination 

 and the spread of the mycelium. 



It is clearly an act approaching those of a madman to 

 use fresh "green " timber for building purposes; but it 

 seems certiin that much improperly dried and by no 

 means "seasoned" timber is employed in some modern 

 houses. Such wood is peculiarly exposed to the attacks 

 of any spores or mycelium that may be near. 



But even when the beams, door-posts, window-sashes, 

 &c., in a house are mide of properly dried and seasoned 

 deal, the danger is not averted if they are supported on 

 damp walls or floors. For the sake of illustration I will 

 take an extreme case, though I have no doubt it has been 

 realized at various times. Beams of thoroughly seasoned 

 deal are cut with a saw which has previously been used 

 for cutting up diseased timber, and a few spores of 

 Meriilius are rubbed off from the saw, and left sticking to 

 one end of the cut beam : this end is then laid on or in 

 a brick wall, or foundation, which has only stood long 

 enough to partially dry. If there is no current of dry air 

 established through this part, nothing is more probable 

 than that the spores will germinate, and the mycelium 

 spread, and in the course of time — it may be months 

 afterwards — a mysterious outbreak of dry-rot ensues. 

 There can be no question that the ends of beams in new 

 houses are peculiarly exposed to the attacks of dry-rot in 

 this way. 



Tiie great safeguard— beyond taking care that no spores 

 or mycelium are present from the first — is to arrange that 



all the brick-work, floors, &c., be thoroughly dry before 

 the timber is put in contact with them ; or to interpose 

 some impervious substance — a less trustworthy method. 

 Then it is necessary to aerate and ventilate the timber ; 

 for dry timber kept dry is proof against " dry-rot." 



The veatilatioa must be real and thorough however, 

 for it has been by no means an uncommon experience to 

 find window-sashes, door-posts, &c., in damp buildings, 

 with the insides scooped out by dry-rot, and the aerated 

 outer shells of the timber quite sound : this is undoubtedly 

 often due to the piint on the outer surfaces preventing a 

 thorough drying of the deeper parts of the wood. 



Of course the question arises, and is loudly urged, Is there 

 no medium which will act as an antiseptic, and kill the 

 mycelium in the timber in the earlier stages of the disease ? 

 The answer is, that mineral poisons will at once kill the 

 mycelium on contact, and that creosote, &c., will do the 

 same ; but who will take the trouble to thoroughly impreg- 

 nate timber in buildings such as harbour dry-rot ? And it 

 is simply useless to merely paint these specifics on the sur- 

 face of the timber : they soak in a little way, and kill the 

 mycelium on the outside, but that is all, and the deadly 

 rot goes on destroying the inner parts of the timber just 

 as surely. 



There is one practical suggestion in this connection, 

 however ; in cases where properly seasoned timber is used, 

 the beams laid in the brick walls might have their ends 

 creosoted, and if thoroughly done this would probably be 

 efficacious during the dangerous period while the walls 

 finished drying. I believe this idea has been carried out 

 lately by Prof. Hartig, who told me of it. The same 

 observer was also kind enough to show me some of his 

 experiments with dry-rot and antiseptics : he dug up and 

 examined in my presence glass jars containing each two 

 pieces of deal — one piece sound, and the other diseased. 

 The sound pieces had been treated with various antiseptics, 

 and then tied face to face with the diseased pieces, and 

 buried in the jar for many months or even two years. 



However, I must nov leave this part of the subject, 

 referring the reader to Hartig's classical publications for 

 further information, and pass on to a sketch of what is 

 known of other -kinds of "dry-rot." It is a remarkable 

 fact, and well known, that Merulius lacrymxns is a 

 domestic fungus, peculiar to dwelling-houses and other 

 buildings, and not found in the forest. We may avoid the 

 discussion as to whether or no it has ever been found 

 wild : one case, it is true, is on record on good authority, 

 but the striking peculiarity about it is that, like some other 

 organisms, this fungus has become intimately associated 

 with mankind and human dwellings, &c. 



The case is very different with the next disease-producing 

 fungus I propose to consider. It frequently happens that 

 timber which has been stacked for some time in the wood- 

 yards shows red or brown streaks, wdiere the substance of 

 the timber is softer, and in fact may be "rotten" : after 

 passing through the saw-mill these streaks of bad wood 

 seriously impair the value of the planks, beams, &c., cut 

 from the logs 



Prof. Hartig, who has devoted much time to the in- 

 vestigation of the various for ns of "dry-rot," informs me 

 that this particular kind of red or brown streaking is 

 due to the ravages of Polyporus vapjrarius. The 

 mycelium of this fungus destroys the structure of the 

 wood in a manner so similar to that of the Merulius that 

 the sawyers and others do not readily distinguish between 

 the two. The mycelium of Polyporus vaporarius forms 

 thick ribbons and strands, but tliey are snowy white, and 

 not gray like those of Merulius lacrymxns : the structure, 

 &c., of the fructification are also different. I have shown 

 in Fig. 19 a piece of wood undergoing destruction from 

 the a:tion of the mycelium of this Po'yporus, and it will 

 be seen how the diseased timber cracks just as under the 

 influence of Merulius. 



Now Polyporus vaporarius is common in the forests,^ 



