Using ryegrass and lucerne silages, investigations were made into the relationship between plant‐cell breakdown, as evidenced by a collapse of the silage mass and by an increase in its electrical conductivity, and the initiation of lactic‐acid production. Changes in the water activity of the juices available as a medium for the silage bacteria were also examined. It has been shown that cell breakdown and the resultant release of the plant juices Is a necessary pre‐requisite for the production of significant amounts of lactic acid during ensilage. The investigation also confirms that the complete exclusion of fresh air from the silage mass can usually be expected to result in cell breakdown within a few hours.

The water activity of juice available for fermentation, after breakdown of the cell walls during the ensiling of plant material, depends largely on the moisture content of the sample. Water activity increases with moisture content, but probably never becomes so high as seriously to limit lactic‐acid fermentation, although high moisture contents have other detrimental effects. With low moisture contents, the limited availability of the juice rather than its lowered water activity is most probably the factor primarily responsible for poor lactic‐acid production.

Ryegrass, clover and lucerne hay were stored a t each of several temperatures between -18" and 36" and moisture contents of (nominally) 7, 12 and 17% for about g months. Dry-matter losses increased with period of storage and with increase in both temperature and moisture, reaching a maximum of about 8%.Changes in the more important chemical constituents were also determined : (i) It was possible that soluble nitrogen contents decreased at temperatures of zx0 and 36" when the moisture content was 17%.(ii) Crude fat contents decreased with increasing temperatures and moistures, the effects of which were independent of each other.(iii) Carotene contents decreased with increasing temperatures, but there was no effect of moisture over the range examined.(iv) Total contents of go%-ethanol-soluble sugars decreased with increasing temperatures, but there was no effect of moisture with contents of 7 and 12%. At 17% moisture both temperature and moisture appeared to enhance the sugar losses.(v) Fructosan contents of ryegrass were not affected by temperature nor was there any change a t moisture contents of 7 and 12%, but a decrease occurred during storage a t 17y0. moisture.Dry-matter losses did not appear adequately to represent nutritional losses when compared with the chemical changes in constituents. - IntroductionDeterioration during the storage of hay depends primarily on the protection provided from weather and vermin, but even when hay is completely protected from the direct effect of factors such as these, gradual changes can still occur in the chemical constituents and these may be accompanied by a loss of dry matter.Apart from the results of investigations concerned with the loss of carotene there is comparatively little published information on the changes which occur in hay during storage, and such reports as are available seldom specify the conditions of storage (temperature and moisture content) with any degree of precision. Watson1 refers to a paper by Honcamp et at. published

Experiments have been carried out to determine the change in the respiration rate of pasture plants after they have been harvested and are being dried. Curves are presented to show that respiration continues throughout most of the drying period although a t a progressively slower rate. It appears t o cease at about 35% moisture content (dry weight basis). Appreciable losses of dry matter usually accompany this continued respiration especially if drying occurs under warm humid conditions. IntroductionLittle information is available regarding the changes in the rate of respiration of pasture plants after they have been harvested and are allowed to dry out as during haymaking.James1 summarises various studies that have been made with detached leaves, but these have been concerned with internal metabolic changes such as carbohydrate starvation rather than water depletion. The usual conditions of experiment confined cut leaves in a dark