366 SCIENCE PROGRESS 



wood, but failed to connect them with the fruit-bodies of 

 Basidiomycetes. He added little that was new concerning the 

 decay of wood. It is evident that the phenomenon was still 

 very incompletely understood. 



In 1878 appeared Robert Hartig's 1 work called Zersetzungs- 

 erscheinungen des Holzcs. It was provided with many excellent 

 illustrations, and threw a flood of light upon the decay of wood. 

 The fungi concerned and their method of action were described 

 in detail. The account included Tramctes radiciperda, T. pini, 

 Poly poms fit hits (Hartigii), P. vaporarius, P. mollis, P. borealis, 

 and Agaricus melleus upon the Coniferae, and Hydnum divcrsi- 

 dens, Thclephora perdix {Stereum frustulosum), Poly poms sulphur- 

 eus, P. igniarius, P. dryadeus, and Stereum hirsutum upon the 

 Oak. Hartig showed that each fungus has a specific action 

 upon wood, so that it is often possible by macroscopic in- 

 spection of a piece of rotten wood to determine the species of 

 fungus concerned in its decay, even in the absence of fruit- 

 bodies. Great attention was paid to the corrosion of cell-walls 

 and their dissolution. The disappearance of starch-grains and 

 protoplasm was observed. Chemical analyses showed that, as 

 wood decays, in many cases it becomes relatively richer in 

 carbon. It was found that some fungi, such as the Dry Rot 

 Fungus, remove the cellulose from the cell-walls, leaving behind 

 a skeleton of friable wood-gum, whilst others, e.g. Stereum 

 hirsutum, delignify and decolorise the lignified membranes so 

 that the cell-walls come to respond readily to the microchemical 

 reactions for pure cellulose. From these and many other 

 observations it became clear that the chemistry of wood decay 

 differs much with the different species of fungi concerned. 



Several other publications of Hartig 2 were more or less 

 devoted to the decay of wood. The chief is his monograph on 

 Merulius lacrimans, 3 the so-called Dry Rot fungus of our houses. 

 It may be pointed out that the term " Dry Rot " is a misnomer, 

 for the fungus can only exist in damp timber, such as occurs in 

 ill-ventilated cellars. Hartig showed that the lungus is able to 

 creep some feet over brickwork, etc., from one beam or board 

 to another, by developing curious strands containing specialised 



1 Berlin, 1878. 



- Wichtige Krankheiten der WaldMumer, Berlin, 1874; Unters. aus d. Forst- 

 bot. Institut zic Miincken, 1883, Bd. 3 ; Pflanzenkrankkeiten, Berlin, 1900. 

 3 Der achte Hausschwamm {Merulius lacrimans), Berlin, 1885. 



