Bd. 23 (1969) H. 2 J. F. Melvin and Ch. M. Stewart, The Chemical Composition of the Wood of Gnetum gnemon irritant action. However, some samples of ayan have been encountered which contain little or no distemonanthin, but substantial quantities of the irritant oxyayanin-B which appeared in the ether extract (King et al., 1954). Thus the potential of ayan for sensitisation may be associated with a small proportion of the timber which is of the latter type.The examples quoted show how a knowledge of the distribution of extractives within the wood structure can help in understanding better their effect on some wood properties. However, why some should be laid down in the cell wall, and others remain in the cell cavity, is a question to be answered when the mechanism of the formation of heartwood substances is better understood. ReferencesEr d t m an, H.

Experiments have been carried out to determine the nature and extent of respiratory losses during the curing of ryegrass hay. Fructosans and the total soluble fructose residues decreased almost continuously throughout the drying period. Sucrose contents decreased initially and then increased. Losses of soluble carbohydrates accounted for most of the actual losses of dry matter determined by weighing. Some protein breakdown was observed. Except in the initial part of the drying the changes in composition did not account for the CO, production.

Bark was stripped, at monthly intervals, from the stems of ten previously-unsampled trees of Eucalyptus regnans F. Muell. The exposed surfaces of inner phloem and outer xylem yielded phloem and cambial saps which were rapidly frozen. After freeze drying to determine the contents of water and dry-matter, the samples were extracted with 80% ethanol. The main components in this extract are low molecular weight carbohydrates and salts of inorganic acids. The carbohydrates comprise stachyose, raffinose, sucrose, galactinol, glucose, fructose, myo-inositol and galactose; sucrose is invariably the major component. The amounts of all components varied widely during the sampling period. Multiple regression analyses showed that season of growth has a significant effect on sucrose, glucose, fructose, total sugars and soluble dry-matter, maxima being recorded near the beginning of autumn and spring, and minima near the beginning of winter and summer; that oligosaccharide and myoinositol contents are significantly related to atmospheric temperature; and that rainfall has a significant effect on the hexose and total sugar contents, saps from the xylem surfaces being more affected than those from the phloem surfaces. The translocated photosynthates in E. regnans appear to be oligosaccharides of the raffinose family and sucrose. Significant negative correlations between oligosaccharides and both sucrose and myoinositol, and significant positive correlations between sucrose and both glucose and fructose, are consistent with enzymic hydrolysis and resynthesis of most di- and oligosaccharides. The biosynthetic demands of developing secondary tissues and/or the fluctuations in composition of sieve-tube assimilates appear to control the composition of the sugars in the saps. Oligosaccharides and sucrose may function as soluble reserve substances as well as translocated photosynthates. It is possible that myoinositolis a key component in the interconversion processes of the sugars; experiments with radioactive sugars tend to lend support to this contention, especially during winter conditions.

Ground ryegrass hay was stored at 25' and about 76% K.H. in nitrogen and also in air to simulate normal storage conditions, and the soluble sugar and dry matter contents were determined at intervals for about one year.Fructosans and oligosaccharides were not affected by these storage conditions. Sucrose was almost completely hydrolysed to glucose and fructose in 21 weeks. This reaction was independent of the storage conditions and could have been due t o enzymic activity.The hexoses did not change appreciably in nitrogen, but in air both glucose and fructose began t o decrease after 21 weeks and only a trace remained after 45 weeks. These losses appeared t o be mainly due to mould. Losses of dry matter followed the same pattern as those of hexose but were consistently less. Introductionthe effects of temperature and moisture on the loss of dry matter and the changes in the soluble sugar contents of ryegrass were described. Losses in dry matter increased with increase in both temperature and moisture.Within the ranges of -18" to 7Q temperature and 7 to 12% moisture, the losses were small, but when the ranges were extended to 36" and IS%, respectively, to include normal storage conditions, the losses increased appreciably and reached a maximum of about 8% under the extreme conditions after 9 months. Losses of sugar accounted for losses of dry matter and, in fact, were usually higher, indicating that some of the decomposition products were retained in the hay. Sucrose was hydrolysed to glucose and fructose, and the hexoses gradually disappeared.The changes outlined above would be expected to affect the nutritive properties as the sugars are a useful source of energy. Restricting losses by control of temperature and/or moisture content may well present difficulties on a large scale, but if the mechanism of the chemical changes involved were known, alternative methods of preservation might be devised. To this end the rBle of oxygen as a contributing factor has been investigated by comparing the effect of storage in nitrogen on the contents of soluble sugar and dry matter with that in air. The possibility of enzymic activity being responsible for hydrolysis of sucrose during the early part of storage has also been examined. Evidence of invertase in hay has recently been reported by tho ma^.^ ExperimentalAbout I kg. of freshly cut short rotation ryegrass (Loliwn sp. N.Z. HI strain) with heads present on 15% of the stems was air-dried in the open, but brought indoors at night. When its moisture content was between 20 and 30%, the drying was completed in a ventilated dryer at 45" for 16 h. The material was then cut into short lengths and ground in a Wiley mill using a + mm. screen. Grinding facilitated sampling during the storage period and was considered legitimate for comparative purposes. The ground material, however, may have been more quickly affected by the storage conditions than if intact hay was stored.The ground hay, 60-70 g. in glass dishes (6 in. dia.) and 3-4 g. in weighing bottles (for determining losses of ...

Experiments have been carried out t o determine the nature of the changes in the nonvolatile organic acids of ryegrass during air-drying. hlalic acid increased and citric and succinic acids decreased throughout most o f the drying period. Quinic acid tonded t o increase. Aspartic acid was not detected in the fresh grass, but appeared early in the drying. Increases in glutamic and aspartic acids were less than those expected from the protein hrealtdown. Pyrrolidonecarboxylic acid lias formed during the latter part of the drying.