SECTIONAL TRANSACTIONS.— B. 321 



uncertainty concerning the relationships between amylose and amylopectin. 

 Work with Miss M. M. T. Plant has thrown light on both these problems. 

 It was found that the essential differences between amylose and amylopectin 

 do riot depend on the phosphorus content. On careful methylation the 

 special characteristics of each modification were retained in the methylated 

 derivatives. Methylated amylopectin yielded on hydrolysis 5 per cent, of 

 tetramethyl glucose, representing a minimum mean chain length of about 

 25 glucose units for amylopectin. Methylated amylose gave the same 

 amount of tetramethyl glucose, and it would appear that the differences 

 between amylose and amylopectin depend on hydration and micellar 

 structure rather than on length of chain. 



Similar work with E. G. V. Percival on methylated glycogen resulted in 

 a yield of 8 • 5 per cent, of tetramethyl glucose, indicating a minimum chain 

 length of about 12 units for this polysaccharide. Glycogen does not retro- 

 grade into an insoluble modification as does amylose, and it would appear 

 that in glycogen the chain length is insufficient to bring about the micellar 

 changes which take place in starch. 



Prof. Dr. H. Mark. — The space model of cellulose. 



The question of the structure of cellulose is an old and fascinating problem 

 of organic chemistry. Many attempts have been made to solve it, but 

 they all failed to reach the final point of linking up structure and properties. 

 The formula of aniline represents to every organic chemist an expression 

 not only of the percentage composition, but also of the properties of the 

 substance. But the expression (CeHioOg);^ for cellulose does not represent 

 anything but the percentage composition. 



There appeared a favourable chance of making progress in regard to the 

 formula of cellulose by building up a model from the molecular point of view. 

 Two stages of new knowledge were necessary. The first step was provided 

 by the very remarkable progress of the researches in the field of sugar 

 chemistry, largely carried on by British chemists. The other was our 

 increased knowledge of the size and shape of molecules, which was mainly 

 the work of Sir William and Professor W. L. Bragg. The combination of 

 these two lines of attack, supported by some results of Freudenberg, 

 rendered it possible to build up a reasonably accurate and detailed model 

 of the cellulose structure which illustrated the peculiarities of its properties 

 and behaviour as a high molecular substance. Such a combination was 

 first made by Sponsler and Dore, and about two years later with more 

 efficiency by K. H. Meyer and his co-workers. 



Mr. W. T. AsTBURY. — Protein fibres and the formation of polysaccharide 

 chains. 



The fruitful combination of the results of organic chemistry with those 

 of X-ray analysis has now defined with some precision the concept 

 of long-chain molecules in the field both of the polysaccharides and of 

 the proteins ; but whereas cellulose appears to be laid down in biological 

 structures as fully extended chains, protein fibres are undoubtedly built up 

 of polypeptide chains in various states of extension. X-rays have as yet 

 revealed only two proteins, the fibroin of natural silk and the (B-keratin of 

 stretched hair, which would appear to be in a fully extended state. Since 

 in natural processes the formation of cellulose and other polysaccharides 

 seems to be brought about through the intervention of proteins, the pos- 

 sibility thus arises that the protein chain may act as a pattern or framework 

 down the sides of which sugar units are laid in order to be linked up into a 



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