396 SECTIONAL TRANSACTIONS.— K*. 



Dr. W. B. R. Laidlaw. — The eiwmies of the Elm Bark Beetle and their 

 significance as a bionomic control. 



This paper gives a brief resume of the Elm Beetle, its appearance, life- 

 history and type of damage. The causes of its attack are discussed more 

 fully on the basis of its being a primary or a secondary pest, along with its 

 relationship in this respect to the attacks of the Dutch Elm Disease 

 (Graphium ulmi). 



The natural enemies recorded are mentioned, those noted in Britain 

 being dwelt on briefly. 



In conclusion, the different types of bionomic pest are considered, the 

 Elm Beetle allotted its apparent place, and the consequent importance of 

 its enemies discussed. It is considered that, although food is the prime 

 factor in the presence and increase of this pest, yet parasites and predators, 

 essentially a secondary factor, may on occasion prove the most important 

 one in the control of the pest, when the problem of dealing with the food 

 factor becomes impracticable. 



Mr. P. Harris. — Research in woodworking. 



This paper deals with the experimental work in this connection being 

 undertaken at the Forest Products Research Laboratory, Princes Ris- 

 borough; describes the methods employed in carrying out the tests, and 

 indicates where further research would be profitable. 



Woodworking research is concerned with investigations into the effect 

 of variation in shape, setting and speed of the cutting tool and rate of 

 movement of the wood on the finish produced, the energy consumption of 

 the machine and the life of the cutting edge. This involves a study of the 

 principles underlying the cutting action of tools and the influence thereon 

 of the elastic properties of the wood. The fundamental knowledge so 

 obtained is of assistance in determining the optimum conditions for 

 machining individual species of timber to ensure economy of working. 

 Determination of the behaviour of the timber when worked under these 

 conditions allows comparison of its working qualities with those of a well- 

 known timber, such as home-grown oak, for hardwoods or imported red or 

 yellow deal for softwoods. Measurement of the energy consumed in 

 certain of the machining operations, estimation of the quality of the finish 

 by means of special recording apparatus, and the opinion of the operator 

 concerning the finished surface and the relative ease of working, provide 

 the data in these investigations. 



Dr. M. H. O'DwYER. — Recent advances in the chemistry of the hemi- 

 celluloses of wood. 



For many years hemicelluloses were considered to be true carbohydrates, 

 but in 1926 the author showed that hemicelluloses from English beechwood 

 contained, in addition, uronic acid anhydrides. On further investigation 

 a certain percentage of methoxyl (2 to 4 per cent.) was found in each hemi- 

 cellulose examined. About 0-4 per cent, methoxyl is present in a substance 

 of a lignin-like character obtained after hydrolysis of the hemicelluloses 

 with 72 per cent, sulphuric acid. There are indications that part, at least, 

 of the remainder is attached to the uronic acid niolecule. 



In the preparation of the hemicelluloses the importance of a knowledge 

 of methods employed in drying the wood, its moisture content at time of 

 preparation as well as sylvicultural details, such as the identification of the 

 species and the age of the wood, cannot be too strongly emphasised. The 



