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These lower slopes, thickly covered with their primitive, close grassland (but now depleted to the utmost) would appear to offer an inexhaustible supply of feed. There alone could the sheep be wintered, nor could they be sent to the high pastures till well on in the spring ; hence, in no few instances, would this grassland be greatly overstocked. So, what with the burning and overstocking, more and more bare ground would gradually appear, the palatable plants would be eaten out, and the tussocks themselves become smaller and weaker. Then, in the early " eighties " of last century, the rabbit arrived from the lowlands and, as the food-supply decreased, crept higher and higher up the mountains. With an eminently favourable climate, abundant food, and a soil suitable for burrowing, or rocks in plenty for their homes, these animals increased enormously, so that with them and the sheep the country became greatly overstocked. Every plant at all palatable was eaten to the ground ; the depleted area ascended higher and higher ; those perennials alone could survive which either were not eaten at all or were furnished with far-extending underground stems, and possessed the power of rapid growth after being cropped close. Then there were the annual species, which possessed great and rapid powers of increase by means of seed, or, in the case of such plants as die yearly to the ground, by far-creeping subterranean stems. It is the addition of the three latter categories to the pasture—mostly foreign plants, with sorrel and wild-geranium the most important as feed, whose advent in quantity was made possible by the new bare ground—which has rendered the sheep-runs still productive, bringing in, accidently—if Nature's methods can be so called—far more good feed than the general aspect of the depleted areas would lead one to imagine. Also, it is the composition, distribution, behaviour, and history of this new flora which first of all brings in a ray of hope for the solution of the regrassing problem. The 1920 Commission listed the following causes of depletion : (1) Burning the tussocks, especially at the wrong season of the year. (2) Overstocking with sheep. (3) Continuous grazing for seventy years without attempt at improvement. (4) Allowing rabbits to become extremely numerous. This latter is the most potent cause of all. (5) The tenure under which the land has been and is held and some of the conditions of such tenures. With regard to deterioration of the grasslands it must be pointed out that the climate, in conjunction with burning, overstocking, and rabbits, is the deciding factor as to how far depletion will proceed. Thus in the extremely wet areas, though there may be great deterioration, no phase of depletion is to be seen. Greater dryness leads to hints at depletion, but it is not until the really dry areas are visited that the maximum of depletion is apparent. In this regard that portion of Central Otago already defined has the misfortune to stand first, but there are areas in the Mackenzie Country, Upper Waitaki, and the Clarence and Awatere Valleys where depletion has long ago reached the scab-weed stage, and where the evolution of depletion can readily be investigated. The effect of a gradually increasing rainfall is well exemplified in travelling from Clyde to Dunedin. Up to Omakau the railway passes through country of a maximum depletion. But at that point the altitude has considerably increased, the rainfall consequently is rather higher, so tussocks once more put in an appearance. Proceeding onwards there are large and small pieces of depletion here and there, but by the time the Maniototo Plain is reached no depletion such as that near Clyde or Alexandra can be seen. On the slopes of the Rock and Pillar there are isolated areas of depletion, but there is no scab-weed. Further on depletion ceases altogether, and foxglove (Digitalis purpurea), a weed of a wet climate, appears in quantity. Even in Central Otago itself the sunny face of a shallow gully may be altogether depleted while the shady face is still covered with tussocks ; this occurs again and again. Another kind of depletion appears on the greywacke mountains of Canterbury and Marlborough. This rock, as already stated, disintegrates rapidly. Once remove the plant-covering and the stony debris beneath is quickly laid bare. Burning tussock near shingle-slips has thus led to their extension. Many such slips once covered with tussock have been again denuded, and, moving downwards, have buried the grassland below. But this matter receives further consideration under the heading of " burning." Of rabbits the 1920 Commission said:— Great unanimity is to be seen in the evidence given by our witnesses regarding the control of rabbits. With but one or two exceptions the witnesses are strongly of opinion that there is one way alone in which rabbits can be reduced to a minimum, or indeed eradicated. This method is by poisoning. On the other hand, trapping is almost universally condemned. With these verdicts we unanimously agree.