MERULIUS 367 



building, and more especially when the ends of joists are 

 built into a wall in the basement of a house. 



Another source of infection of new wood is due to the 

 frequent presence of old infected beams and boards in timber- 

 yards, from which spores are being constantly diffused, or by 

 the spreading of mycelium from such old wood to the new 

 stock stored in the same yard. 



Broadly effused, usually resupinate, soft and rather moist, 

 yellowish-brown in the centre, margin whitish. Spores rusty 

 yellow, elliptical, 10-12x5-6^. 



Dr. Carpenter's experience of dry-rot is as follows : { I 

 know a house into which the rot gained admittance, and 

 which, during the four years we rented it, had the parlours 

 twice wainscoted and a new flight of stairs, the dry-rot 

 having rendered it unsafe to go from the ground floor to the 

 bedrooms. Every precaution was taken to remove the decay- 

 ing timbers when the new work was done ; yet the dry-rot so 

 rapidly gained strength that the house was ultimately pulled 

 down.' 



The idea of excluding dry-rot from a building, by hermeti- 

 cally closing all outer air from spaces between joists and 

 flooring-boards, etc., is an entirely wrong principle, because 

 as a rule the disease is already present in the wood when 

 used. An attempt of this kind was made in the case of a 

 mansion recently erected, and the result proved disastrous. 



The ends of joists that are going to be built into a wall 

 should first be thoroughly soaked with creosote, as should all 

 wood showing red-stripe. 



Creosote is much more effective than gas-tar, as the latter 

 prevents the wood from drying, and thus actually favours the 

 growth of the fungus, if present in the wood. The surface of 

 flooring-boards coming into contact with ' deadening ' material 

 should first be brushed over with methylated spirit containing 

 corrosive sublimate in solution six ounces to one gallon. 

 The spirit soon evaporates and leaves a coating of corrosive 

 sublimate on the boards, which prevents the growth of the 

 fungus. 



A constant source of trouble arises from the use of 

 ' pugging ' or deadening material before it is thoroughly dry. 

 Coarse sand is the best to use for the purpose, Coal-dust, 

 cinders, or humus should not be used, as favouring the 

 fungus, whose spores germinate in moisture having an alka- 

 line reaction. 



