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of defence. Only those who live in the past demand that Great Britain should concentrate her energy upon the Navy. As much can be said without in any way belittling the great importance of our Fleet. Moreover, air defence is likely to become increasingly important with the advance of the science and art of aviation. the latter purpose, aeronautical research in its widest sense is of the utmost importance. It is hoped, therefore, that as soon as funds permit, the Government will arrange for a fuller measure of encouragement in that direction-by a somewhat increased grant-seeing that any future wars seem likely to be largely based on scientific research.

In the event of a Ministry of Defence being, in due course, established it is quite on the cards that Civil Aviation and Aeronautical Research may be embraced either under a revived Ministry of Transport or possibly under either the Board of Trade or the Post Office. Meanwhile, it can certainly be stated that the Department under the especially business-like administration of Sir Samuel Hoare and, on the other hand, of Sir Sefton Brancker, the eminently worthy successor to Sir Frederick Sykes, forms a good example of the recognition by the present Government of the great importance of aviation. Further recognition is needed, however, by the Air Minister becoming a member of the Cabinet equally with the First Lord of the Admiralty and War Minister. So far, however, our Air Ministers have been a sort of Cinderella. It is good that so able an ex-Air Minister as Lord Weir has recently become a member of the Committee of Imperial Defence, but that is not enough.

The increasing activities of the Air League of the British Empire will, it is to be hoped, mean that no Government will ever be allowed to lapse into the neglect of aviation that had scandalously prevailed— even allowing for due economy-before the present administration came into power. Thus, in the interests of National and Imperial Defence and of Trade, the Air League should receive a still further measure of support from every British citizen worthy of the name.

CHARLES BRIGHT.

It is a source of much satisfaction that since these lines were written the Secretary of State for Air has become a Cabinet Minister.

Art. 6.-PROBLEMS OF ACCLIMATISATION.

1. The Naturalisation of Animals and Plants in New Zealand. By the Hon. G. M. Thomson. Cambridge University Press, 1922.

2. Report on the Damage done by Deer in the Forests and Plantations in New Zealand. State Paper. Wellington.

New Zealand, being a group of islands separated by a thousand miles of ocean from any other extensive land area, has long been a fascinating field of research to the student of biology, especially for the light which an investigation of its flora and fauna throws upon the problems of evolution.

When Captain Cook landed in New Zealand in 1769, there were only four land mammals to be found in the country-a small native rat, a dog, supposed to have been introduced by the Maoris, and two species of bats. But its rich virgin forests-tropical in their luxuriance and beauty-abounded with bird-life, including many types not to be found in any other part of the world. These have been an unfailing source of interest to the biologists, as have also the insects, earthworms, and reptiles, particularly the fearsome-looking tuatara, supposed to be the oldest form of life surviving from ancient times on this planet. To the botanist, particularly the plant ecologist, the plant-life of New Zealand is equally rich in the opportunities offered for fruitful research. With the advent of a European population, however, the aspect of the country, from a naturalist's point of view, has become entirely changed, save only in a few remote districts, difficult of access, and even those are gradually coming under the influence of an alien invasion. The beautiful forests were destroyed in the most reckless fashion to make room for the farms of the settlers. Magnificent timber trees, which would now be worth in the aggregate several millions of pounds, were deliberately burned so that grass seed could be sown in the ashes. With the trees went, of course, the birds which fed on the berries or the honey-producing flowers.

But it was not only by direct destruction of this kind that the white man has altered the face of nature in New Zealand. Some of the efforts he made, with the Vol. 240.-No. 476.

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best intentions in the world, to supplement the animal and vegetable resources of his own home, have proved as disastrous as the process of creating a wilderness of blackened stumps and calling it settlement. One illustration only need be cited. Some of the early settlers, inspired, no doubt, by memories of the boyish delights of ferreting and shooting rabbits, introduced a few pairs of rabbits into the colony, and turned them loose. The results have been appalling, especially in parts of the South Island. The rabbits increased at an incredible rate, and at one time it looked as if sheep-farming, the chief industry of the country, had been made impossible. In the 'seventies and early 'eighties the pest had overrun the greater part of Otago, as well as the whole of Southland. The fine natural grasses on which sheep and cattle grazed were almost totally destroyed. Not only did four rabbits eat as much as one sheep-according to the most moderate computation-but the fouling of the land spoiled it for grazing or stock of any kind. Sheep perished from starvation by hundreds of thousands, and the majority of the squatters were ruined. remember seeing an advertisement in the Government Gazette' offering 100,000 acres of grazing country for a merely nominal rental of ten or twelve pounds a year. The explanation, of course, was that the cost of keeping down the rabbits, if it could be accomplished at all, would have amounted practically to a prohibitive rental in itself. When the true nature of the pest became manifest the most frantic efforts were made to cope with it. In the early days, hunting with dogs, shooting, digging out the warrens, poisoning with various baits and trapping were the methods adopted. Later, wire netting fencing, the introduction of stoats, weasels, and ferrets, fumigating the burrows with poisonous gasessuch as carbon disulphide and hydrocyanic acid—and the stimulus given to trapping by the export trade in frozen rabbits and rabbit skins were relied upon. At one time proposals were made to introduce disease among the swarming millions to bring about their extermination; but nothing was done in this direction.

It was not until 1895 that any check was observable, but from that time there has been a steady diminution, and it may now fairly be said that the plague is stayed,

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although owners of land have to be continually on the watch, and find it necessary to expend large sums of money annually to prevent these prolific animals from again getting the mastery. During the War, when the best rabbit skins fetched as much as 38. 10d. per skindoubtless for the manufacture of 'coney seal' coats for munition workers-it looked almost as if the curse were about to be turned into a blessing. The chief profit was made, however, not by the owners, but by the rabbiters. Labour was scarce-most of the young New Zealand countrymen who were able-bodied had gone to the front-and mere boys earned as much as 25l. per week at rabbiting. The price has since gone back to about 8d. per skin. In 1921 the value of rabbit skins exported was only 448,1801., while the economic waste caused by the rabbits, according to Mr Thomson, probably runs every year into millions of pounds. Trapping is not much thought of by practical farmers as a means of keeping down the pest. The trappers catch rabbits as long as it pays them to do so, but take care to leave a nucleus for future operations. Some authorities think that the decline of the rabbit is principally due to natural causes. Mr Begg, of Mosgiel, quoted by Mr Thomson, says:

'Hardly two men will agree as to the cause of the decline in the rabbit, and I will just state my theory for what it is worth. The grey rabbit, when first introduced, found himself in very congenial surroundings. There was abundance of food and shelter, and the ground was absolutely clean, never having been grazed by rabbits previously. These favourable conditions gave a tremendous fillip to the vitality of the rabbits and stimulated their powers of reproduction. They increased at a rate that I believe is not even approached in the worst infested parts of Otago to-day. No efforts at checking them had the slightest effect, and they passed over the country like a prairie fire. After a time the original con ditions no longer existed. Food became scarce, the land was foul with rabbits, disease appeared among them, and their fertility decreased. No doubt improved methods of dealing with them hastened their reduction, but I firmly believe that the principal factor in their decrease was lessened fertility, due to the first great spurt to their vitality having spent itself.'

It is hardly possible to doubt that the strenuous

efforts of the landowners-stimulated by penalties imposed by law for failure to keep down rabbits-have had considerable effect. The subdivision of large estates into smaller holdings, which has been a marked feature of land settlement in New Zealand during the last few years, has been beneficial from the point of view of coping with the rabbit, as in other respects. Mr Begg, who is disposed to put in a good word even for that 'puir deil,' says: 'Many a successful farmer of to-day got a start as a rabbiter. The killing of rabbits actually became one of the principal industries of the province. Their presence directly led to the subdivision of large estates, and may have been quite as effective as all the legislation on the subject.'

If, however, you once interfere with the balance of Nature there is no saying where the effect will end. The introduction of rabbits, as Mr Thomson points out, has had a lasting effect on acclimatisation generally :

'Before their advent partridges and pheasants had become numerous, but they have entirely disappeared in Otago. In the effort to cope with the rabbits the country was annually sown with poisoned grain. This had a disastrous effect both on native and imported game. Had rabbits not become a nuisance it is unlikely that weasels and other vermin would have been introduced. These animals are largely responsible for the decrease in the number of native birds, and also make the successful introduction of new varieties more difficult.'

In an eloquent passage Mr Thomson describes the sentiments which led those who settled in New Zealand from time to time to set about introducing into their new homes plants and animals associated with the home from which they came:

"The early settlers of New Zealand found themselves in a land which, as far as regards climate and natural conditions, seemed to them to reproduce many of the best features of the homeland from which they came. They thought with affection and with the glamour of youthful remembrance of the lakes and rivers, the woods and the fields, the hills and the dells of that homeland. They recalled the sport which was forbidden to all but a favoured few, but which they had often longed to share in-the game preserves, the deer on the mountains or in the parks, the grouse on the heather-clad