SECTIONAL TRAN8ACTI0NS.— K*. 411 



Tuesday, September 9. 



Mr. W. R. Day. — The Relation of Frost Damage to Larch Canker. 



The general view with regard to tlie development of larch canker is that the ftingus 

 Daayscypha calycina (Schum) Fuckel is the cause of the canker formation, and that 

 the cambium is killed by the fungus during the winter. The evidence for the latter 

 point is that no new wood is ever formed at the time the cambium dies. In this 

 paper it is endeavoured to demonstrate (a) that the cambium not infrequently dies 

 in the spring, and (6) that the cause of death is frost, in many cases at least. Cankers 

 of typical form may be caused by frost, and anatomical evidence is brought forward to 

 demonstrate this. The larch canker fungus is always present in these cankers, where 

 it lives apparently as a sapropliyte. This work is preliminary to further study, and 

 no claim is made here that D. calycina is not in many cases the cause of canker 

 development. 



Dr. M. C. Raynee. — Observations on the Behaviour of Armillaria mellea 

 in pure Culture tvith certain Conifers. 



There are a number of puzzling features in the reactions shown by Conifers to 

 attack by Armillaria mellea. 



In this paper an account is given of observations on pure cidtures of seedlings 

 of two conifers, Corsican Pine and Douglas Fir, exposed to infection by actively 

 growing rhizomorphs of Armillaria mellea. The facts described will be illustrated bj^ 

 lantern slides of photographs at various stages of growth. 



This common tree-attacking fungus has features of special interest to students 

 of mycorrhiza and the evolution of the mycorrhizal habit. It belongs to a group of 

 fungi that include most of the known or suspected mycorrhiza -formers of trees ; 

 moreover, in the case of at least one herbaceous host species, it is recorded as forming 

 an association of balanced parasitism sometimes described as symbiosis. 



Certain conclusions deduced from the experiments are offered as a basis for 

 discussion. 



Mr. K. St. G. Cartwright and Mr. W. P. K. Findlay. — The Diagnosis of 



Decay in Timber. 



After a brief survey of the rough methods used by foresters, timbermen and others 

 for determining the presence of fungi causing decay in timber, this paper describes 

 methods which have been developed in order to recognise the presence of a fungus in 

 the very early stages of an attack and the means whereby the identity of the causal 

 fungus may be established. Many different species of fungi cause much the same 

 general effect on any one species of timber, and frequently the microscopic examina- 

 tion of the decayed wood gives bat little further information. It has been found that 

 most of the wood-destroying fungi when grown in pure culture on artificial media 

 show differences whereby they may be recognised, especially if a standard culture 

 obtained from a named sporophore is available for comparison. Cultures of all the 

 more important wood-destroying fungi have been collected by the authors, working 

 for the Forest Products Research Laboratory, Princes Risborough, and these are now 

 being classified and described. 



Wednesday, September 10. 



Mr. R. A. G. Knight. — The Moisttire Content of Wood in Relation to Hygro- 

 metric Conditions. 



Timber in general use assumes a moisture content which is dependent on surround- 

 ing hygrometric conditions, and will vary as the state of the atmosphere changes. 



After a preliminary discussion, moisture content — temperature humidity equi- 

 librium curves, determined by experiment at the Forest Products Research Laboratorj', 

 are presented. 



The practical importance of the work is indicated by an outline description of an 

 experiment to ascertain the most suitable moisture contents of woods fcr furniture 



