104 DRY-ROT. 



excites astonishment, now that we know the intimate coi.stitution 

 of wood. We know, in fact, that amon^ the number of sohible 

 principles which impregnate the woody tissue, there is an azotized 

 matter analogous in its composition to those that exist so abundantly 

 in all the ordinary esculent vegetables. There is, therefore, in wood 

 ample nourishment for the insects which we find living on it ; and 

 if I state now (reserving to myself the opportunity of demonstrating 

 the fact) that all organic azotized matter becomes an active manure 

 by decaying, we shall understand how it happens that plants, which 

 have the power of living in dark, warm, and damp places, wax and 

 multiply in the joistings of houses, and in the ribs and planks ol 

 hips, causing a dry rot, which separates the integral layers of the 

 wood, and reduces the strongest beams to dust. 



The rapidity with which wood is, in some circumstances, devour- 

 ed by insects is almost incredible. Some years ago the thermites, 

 or white ants, spread in such strength through the docks and ar- 

 senals of Roehelle and Rochefort, that in a very short space of time 

 serious damage was done. A learned entomologist, M. Audouin, 

 commissioned by the ministry to take information on the subject, 

 reported that the ravages committed by these insects had been very 

 considerable. But it is principally in warmer climates, where the tem- 

 perature is steady throughout the year, and where there is no winter, 

 that the thermites occasion the most alarming injury. At Popayau, 

 for example, it is difficult to meet in a building, even of recent con« 

 struction, with a piece of wood which is not gnawed and ant-eaten. 

 The hardest and most compact woods do not always resist the at- 

 tacks of these insects, which, further, do not spare every kind of 

 odorous wood, cedar for instance. In such countries it is altogether 

 imp. ssible to preserve books and papers. I remember, in connec- 

 tion vith this matter, that having received instructions to examine 

 the archives of Anserma, one of the oldest towns in Popayan, in 

 1830, I found nothing but books illegible and in pieces ; neverthe- 

 less, the date of the documents, which it was my business to con^ult, 

 could not have been older than the year 1600. 



The dry rot, which results from the development and growth of 

 cryptogamic plants upon wood, is the curse of navies. Mr. Knowles 

 is of opinion that this disease of timber has been known from the 

 most remote antiquity ; he believes that he can even recognise dry- 

 rot in the sore called house-leprosy, mentioned in the 14th chapter 

 of Leviticus. A ship attacked by dry-rot, becomes in a very short 

 space of time unfit for sea. The Foudroyant of 80 guns is often 

 quoted as an instance of its destructive powers : launched in 1798, 

 she had to be taken into dock and almost rebuilt so soon as 1802.* 



The fungi which induce dry-rot have been studied by Sowerby. 

 Mr. Knowles signalizes two species in particular ; one of which he 

 describes under the name of Xylostroma giganteum, the other under 

 that of Boletus lacrymans. The Xylostroma does not extend beyond 

 the part where it is developed ; but the Boletus, on the coalrary, it 



* Pupia, Ann. de Chimle, t. xvii. p. 290i 



