46^ 



*!ife f Topical acinic OLfu^isi*. 



[JaK I, i88y. 



THE DEY ROT FUNGUS. 



Mkrumus lachrymans.— Thedry rot fungus is one of 

 the most widespread aud destructive of all fungi. 

 It is espe ially common and well known on the 

 squared timber of ill-ventilated buildings, and from 

 dressed wood it will quickly spread to walls, whether 

 built of stone, brick, or concrete ; it will often grow 

 through the mortar of a thick wall, and perfect itself 

 on the bricks both outside aud inside. We have seen 

 it growing on damp concrete between the girders of 

 iron fire-pi'oof floors, and seen it spread from wood on 

 to plate-glass, aud perfect itself on the latter subs- 

 tance whilst drawing its nourishment from the wood. 

 In wine cellars it will spread from the wood work 

 and walls to the bins and even to the corks of wine 

 bottles. The mycelium of ik; fungus will luxuriate 

 between the cork and the neck of the bottle ; a 

 slight attack of this sort is said to make the wine 

 " corky."' 



The dry rot fungus prefers .the squared unpolished 

 wood of coniferous trees as a substratum on which to 

 luxuriate, but we have seen it on polished Mahogany, 

 and it will spread from other woods to Teak aud 

 destroy Teak-built ships. It is not UDCommon on the 

 fallen timber of Pine woods, but, like some other 

 plants, it has long been peculiarly associated with man 

 aud his dwellings. It destroys churches, houses, ships, 

 bridges, railway sleepers, telegraph poles, and many 

 other objects. It must not be assumed, however, that 

 the true dry rot fungus is the sole, depredator. 

 There are twelve British species of Merulius, inclusive 

 of M. lachrymans, and several of these appear at 

 times in our houses. We have seen M. coriun al- 

 most as destructive as M. lachrymans. In addition 

 to the dry rot fungi, it is by no means uncommon 

 to find buildings destroyed bj' different species of 

 Polyporus, Lentinus, and other fuogi. 



Merulius was so named by Fries on account of the 

 shallow pores or wrinkles of the spore-producing sur- 

 face, and lachrymaus on account of the drops of 

 moisture, like tears, whi'ih stad the fruiting surface 

 of the fungus when growing in full vigour. 



The upper part of the accompanyiug illustration 

 (fig. 125, p. 629) shows a small plant of a dry-rot 

 fungus ; the circumference is white or livid in colour, 

 and thick and fleshy. The whole plant is fleshy and 

 almost meaty when cut. The odour is very strong 

 and Mushroom-like. The livid rirn consists of trans- 

 parent interwoven fungus tubes and cells as illustrate], 

 enlarged 400 diameters at c ; tubes of this nature 

 and size also form the entire i)ase of the fungus. 

 The fungus cells or tubes break down the substance 

 of the wood upon which they grow and tran.sport 

 the juices of the wood to the fungus for nourishment. 

 The central part of the surface of the ilerulius is 

 rich reddish-brown in colour and indented with coarse 

 shallow pores or wrinkles, as illustrated in the upper 

 figure. A reddish livid juice is exuded from all parts 

 of this fungus ; this juice stains every object with 

 ■which it comes iu contact. A section of the wrinkled 

 surface i.s shown natural size at a. Every part of 

 the reddish wrinkled surface produces spores, the same 

 portion distills drops of moisture, chiefly derived from 

 the wood upon which the fungus grows. By breaking 

 .down the substance of the wood and extracting its 

 juices, the timber is ultimately left in a atate little 

 better than dry sawdust or powder, hence the popular 

 name of " dry rot/' a curious name for a naturally 

 wot or " weeping '' fuiigus< If a very small fragment 

 is cut from the wrinkled surface of an example of 

 Merulius lachrymans, and a very thin transparent 

 slice is then removed from the exposed surface and 

 examined with a microscope it will be seen, if en- 

 larged 400 diameters, as at h. The coarse transparent 

 tubes of the base of the fungus become much 

 narrower as they gradually grow up towards the 

 brown wrinkled surface; aud in the latter position 

 they support tall colouvless cells or bladders as shown ; 

 eacii tall bladder throws out four minute horns or 

 spore-supporters at its apex, and on each horn an 

 ovel spore of rich brown colour is borne, as illustrated, 

 When the rips spores fall from their supports 

 ^u to damp wood in close confined »ir, tljey g^rwiu- 



ate and throw out fine mycelial tubes, the tubes 

 penetrate the sweating wood and Eoon produce a 

 perfect dry rot fungus by drawing from the wood 

 the material necessary for the life and well-being 

 of the fungus. The fungus continues to grow till 

 the supporting timber is completely exhausted ;ind 

 reduced to tinder or dust; the fungus itself no v 

 perishes, but not before it has produced mj-riads 

 of spores which have probably been carried away by 

 currents of air to destroy other damp wood, or wood 

 m damp places. The dry rot fungus will under 

 favourable conditions attain a very large size, its 

 dimensions appear, in fact, to be only limited by 

 the size of the object or material on which it grows ; 

 we have seen huge thick growths, like large pancakes, 

 a yard or more in diameter. As the growth of the fungus 

 is as rapid as it is exhaustive, it follows that when 

 dry not once gets a footing in an ill-ventilated 

 building the work of destruction is rapid and com- 

 plete. Floors rot, roofs fall, galleries collapse, and 

 window sashes turn to powder and drop out. As 

 the air of the infe.sted building is full of dry rot 

 spores it is useless to replace old ^vood with new, 

 for new wood merely supplies fresh food for the 

 fungiis. Sometimes improved ventilation is beneficial 

 but it is impossible to really cure dry rot, and almost 

 if not quite impossible to stop its progress when once 

 well started, as the fungus is always ready to in- 

 vade various other materials in addition to wood. 

 To keep well clear of dry rot its attacks should 

 be prevented. 



Petroleum will quickly destroy the dry-rot fungus, 

 and prevent its reappearance, but it is so extremely 

 dangerous to thorougly soak a building or ship with 

 petroleum, that the remedy is as bad or worse than 

 the disease. Burnett's mode of preserving timber is 

 by the application of chloride of zinc ; this, without 

 injuring the wood, has a tendency to protect it from 

 destruction. Kyan's method (hence the term kyanis- 

 ing) consists of the use corrosive sublimatic, but this 

 material can only be applied effectually on dry (as 

 opposed to wet or damp) timber. Margary's method 

 (hence the term margarising) consits in the appli- 

 cation of the sulphate or other salts of copper. 

 Bethell's method, which is the best, consists of 

 "creosoting" the wood, by the application of coal 

 tar or oil of tar. This substance does not get 

 driven out of timber by moisture, whereas all the 

 salts of metals fail in this direction. Ooal tar, a 

 material which looks like treacle, is derived from 

 coal in the process of gas-making. When coal tar 

 is distilled, light oils, heavy oils, and pitch (the 

 residuum) are produced : the oils heavier than water 

 are the " creosote " of Bethell. The most effective 

 heavy creosote for timber preservation is derived 

 from the best Newcastle coals, a less valuable mate- 

 rial is distilled from IMidland coals. A good deal 

 of our knowlege of wood preservation, as 

 possessed at the present day, seems to have been 

 known in part at least to the ancient Egyptians, who 

 filled the pores of their wooden statues, columns, 

 &c.,— to say nothing of the grand-mummies (I), — 

 with oils and bitumen, 



Mr. Baulton states that Fir timber is capable of 

 taking up from (30 to 1 tO gallons of water to the 

 load of 50 cubic feet, he also states that he has 

 extracted 60 gallons of water from a load of railway 

 sleepers. In the process of creosoting the timber is 

 first made (juite dry and the extracted water is then 

 replaced under heavy pressure, by oil of tar. IMore 

 than one patent has been taken out for " creosoting," 

 and the efficacy or otherwise of creosoted timber 

 depenils on the quality and constituents of the oil 

 of tar and the method of forcing it into the pores 

 of the timber. 



The proper auHseptic treatment of wood is a sub- 

 ject of the highest importance when studied iu refer- 

 ence to the preservation of telegraph posts, railway 

 sleeper.?, piles for harbom's, ships' timbers, and to 

 cases where wood must of necessity be exposed to the 

 action of water, damp earth, or moist air, but in 

 buildings which arc designed to be constantly kept 

 dry uo creosoting i§ necessary. In horticultural 



