Some of the indigenous species are quite as aggressive, or even more so, than any of the introduced. In primeval New Zealand each would have its place in the association to which it belonged-there would be no aggression; but when the balance of nature was upset by the fire or cultivation of Maori or European, then the plants best equipped for occupying the new ground become dominant, their "adaptations" for that purpose fortuitously present. The miles on miles of Leptospermum scoparium and Pteridium esculentum were absent in primitive New Zealand. So, too, the pastures of Danthonia semiannularis in Marlborough, and the many acres of Chrysobactron Hookeri in the lower mountain region of Canterbury. Celmisia spectabilis, an apparently highly specialized herb for alpine fellfield or tussock-steppe conditions, is now on the increase in many montane parts of the Ashburton-Rakaia mountains and valleys, owing to its being able to withstand fire, the buds being protected by a close investment of wet decayed leaf-sheaths. Nor are all the introduced species aggressive, by any means. Some can barely hold their own; others are limited to certain edaphic conditions. Thus, Glaucium flavum, Crantz, occurs, as yet, only on the coast of Wellington, chiefly in the neighbourhood of Cook Strait. It is confined to gravelly or stony shores, and appears unable to grow on the clay hillside. And yet where the latter is, in one place near Lyall Bay, covered with gravel there is a large colony of the plant, whence none have found their way on to the adjacent hillside. Lupinus arboreus, now so common on New Zealand dunes, appears unable to spread beyond the sandy ground1. The fortuitous introduction of foreign species of animals and plants into the country has been going on continuously since the European settlement of New Zealand began. This was first brought to my notice when we settled in Southland, and took up a farm there. In 1870 we imported from Messrs Lawson and Sons, Edinburgh, a quantity of grass-seed for permanent pasture invoiced to contain the following species: In addition to these the following appeared, the ground being newly broken up-and having never previously been cultivated: 1 The latest expression of views on this interesting subject will be found in Dr Cockayne's New Zealand Plants and their story, Chap. X (Wellington, 1919). Cuscuta Trifolii or Trifolium repens and T. pratense. Similar experiences have occurred, but have not been recorded, many thousand of times in the intervening years. In all agricultural seeds imported into the country a certain proportion of seeds of foreign plants is introduced, amounting in the aggregate to many millions. The number of those which do not grow, or if they germinate, do not succeed in establishing themselves, is very remarkable. In recent years the Agricultural Department has set up a seedtesting bureau at its experimental farm of Weraroa, near Levin, and has drawn up a "List of Extraneous Seeds found in Commercial Samples of Seed, showing relative frequency of occurrence of each, and whether harmful or otherwise." The list for 1916 contains the names of 224 species of plants, all except three being introduced species. It included the following twenty species which have never yet been observed growing in the country, although evidently the seeds are introduced from time to time: In this connection it is very remarkable to notice the number of foreign seeds introduced into this country with agricultural seeds, but which do not grow1. 1 The following newly introduced grasses were placed in the trial beds at Ruakura Farm in 1909: Agropyrum tenerum (slender wheat- A. Smithii (western wheat-grass, Bromus pacificus Bouteloua curtipendula Briza geniculata Chloris abyssinica C. barbata Elymus submuticus E. giganteus Erianthes ravennæ Ecrucaria cuspidata Panicum sp. Giant-couch Paspalum stoloniferum Phalaris cærulescens Piptatherum Thomasii Sporobolus Wrightii Vilfa arguti Chapter XV ACCLIMATISATION WORK; GENERAL CONSIDERATIONS In the various experiments made in the attempt to acclimatise, or, as I prefer always to call it, to naturalise, certain animals, very little forethought was given as to the possibilities of any particular case. We are wise now after the event, and we blame the acclimatisation societies, the Government, or various private individuals for mistakes made. But it is doubtful whether we would have done any better ourselves. There is one curious fact which never seems to have entered into the minds of most if not all of the acclimatisation enthusiasts, viz., the migratory character of the species which it was sought to establish in this new land. This applies especially, of course, to the birds. It probably explains the failure of certain species to become established here. Thus the blackcap (Sylvia atricapilla) and nightingale (Daulias luscinia) are summer visitors only in the British Isles, the former wintering in Southern Europe, Northern and Tropical Africa, and the latter in Tropical Africa. Only a very few examples of these two species were introduced, but it would not have mattered how many had been successfully conveyed to New Zealand, and liberated, the result must have been the same. After a time the birds would almost certainly have become possessed by the desire to migrate to a warmer climate, but having no hereditary line of migration to follow, they would probably have proceeded northwards and perished at sea. There is no information at all as to the effect of the migratory instinct on birds which have been taken from their own country to a totally different hemisphere. We can only assume that the desire to migrate would come on them strongly, and if so, it would inevitably prove fatal to them in an island country like New Zealand. Seebohm (in Siberia in Asia, p. 196) states that the migration of birds follows ancient coast-lines. The migration from the south of Denmark over Heligoland to the coast of Lincolnshire seems to correspond so exactly with what geologists tell us must have been the old coast-line, that it is difficult to believe it to be only a coincidence. The following species which have failed to become established in New Zealand are purely winter visitors in Britain: brambling (Fringilla montifringilla), white-fronted goose (Anser albifrons), brent goose (Branta nigricans), and grey plover (Squatorola helvetica). These birds are in the same category as the previously named group. The following species are partial migrants, being resident in Britain at all seasons, but having migratory representatives which visit Britain in summer, and which winter somewhere to the south: linnet (Linota cannabina), twite (Linota flavirostris), redbreast (Erithacus rubecula), and teal (Nettion crecca). The following, which have also failed to establish themselves, are partial residents, but are also largely winter visitors in Britain: gadwall (Chaulelasmus streperus), pintail (Dafila acuta), wigeon (Mareca penelope), pochard (Nyroca ferina), and golden plover (Charadrius pluvialis). As several writers on the subject of migration have pointed out, racial forms of certain species appear regularly in Britain, either as seasonal visitors or as occasional guests, and these include species of which resident representatives occur all the year round. Again in catching birds for exportation, it is impossible for the professional bird-catcher to ascertain whether the specimens captured belong to residents or to migrant races. The probabilities seem to me to be that they mostly belong to the latter, because the bird-catcher goes where he knows or expects to find birds gathered together in flocks, and these mostly come together preparatory to migration. It is quite possible that the specimens of linnets and twites brought to this country were migratory representatives of these species; this may explain their failure to remain here. The following birds, all of which have become naturalised in New Zealand, are also resident in Britain all the year round, but it is well known that there are numerous migratory races of them: rook (Corvus frugilegus), starling (Sturnus vulgaris), goldfinch (Carduelis elegans), greenfinch (Ligurinus chloris), skylark (Alauda arvensis), song thrush (Turdus musicus), hedge-sparrow (Accentor modularis), Mallard (Anas boscas). In a note to his list of partial migrants, Clarke states that: "Starlings marked in Britain have been recovered in France, Greenfinches in France, Linnets in France, Song Thrushes in France and Portugal, and Mallard and Teal in Germany." Seebohm also (in Siberia in Europe, p. 245) says: Many birds, such as the Robin, the Blackbird, the Song Thrush, etc., which are resident in England, are migratory in Germany. There is every probability that it is only within comparatively recent times that these birds have ceased to migrate in England, and we may fairly conjecture that should the English climate remain long enough favourable to the winter residence of these birds, they will develop into local races, which will eventually have rounder and shorter wings than their Continental allies. In connection with the naturalisation of the rabbit, it is interesting to note that the earlier introductions all failed to establish themselves There were rabbits in Otago at three or more different localities in the very early days of settlement. None of these colonies succeeded, but we cannot tell now to what particular breeds they belonged. It is just possible that they were of races which had been long under domestication, which would certainly be the kind that would carry best, and would be the most likely to be brought out in immigrant ships as pets. It was not till after the introduction of grey rabbits in the sixties, rabbits of a particularly aggressive and vigorous type, that these animals became a nuisance. Very little is known about the movements and migrations of fishes in the sea, and in New Zealand practically nothing definite has been recorded. The date of the movements of the eels from the Waikato to the sea; the invasion of the southern rivers by lampreys in October; the northern drift of vast shoals of Clupea (pilchards and sprats) along the east coast of Otago in January and February-such general facts as these have been recorded, but no detailed observations have been made. It is to be regretted that steps were not taken in the past to mark specimens of Atlantic salmon (Salmo salar) when liberating them, in order to try, if possible, to gain some knowledge of their movements. The fact is that for over fifty years in this country, and for even longer in Tasmania, the young of this species have been turned out into the rivers by the million. They have found their way to the sea, and yet none have ever returned. What comes of them is a mystery regarding which no solution has ever been offered. Another interesting case is the failure, so far, of the European lobster (Homarus vulgaris) to appear again in our seas. In this instance numerous larvæ-averaging at a low estimate 100,000 per annum, and in many cases at a fairly advanced stage of development—have been liberated from the Portobello Fish Hatchery into Otago Harbour, for twelve years past. In addition, several adults were liberated within the harbour. Allowing even ten years for a lobster to come to sexual maturity, when all the larger crustaceans usually begin to move about in large shoals, there has been ample time for adult specimens to show themselves, if they are in New Zealand waters, either near the Otago coast, or further north, whither the northerly current would carry them while they were still in the free-swimming stage. It is hoped, and with good reason, that they will appear some day in quantity, but there are no indications so far. The same remarks apply to the European edible crab (Cancer pagurus) of which between thirty and forty million larvæ, and some adults, have been liberated. Periodical migration of Crustacea-large and small-does take place in the seas, the causes of which are quite unknown, so both the |