84 A C C A C C clapping of hands, but this distinction in the usage of the words is by no means uniformly maintained. Among the Eomans acclamation was varied both in form and purpose. At marriages it was usual for the spectators to shout lo Hymen, Hymencee, or Talassio; a victorious army or general was greeted with lo triumphs ; in the theatre acclamation was called for at the close of the play by the last actor, who said, Plaudite ; in the senate opinions were expressed and votes passed by acclamation in such forms as Omnes, omnes, jEquum est, Justum est, &c ; and the praises of the emperor were celebrated in certain pre-arranged sentences, which seem to have been chanted by the whole body of senators. The acclamations which authors and poets who recited their works in public received were at first spon taneous and genuine, but in time became very largely mercenary, it being customary for men of fortune who affected literary tastes to keep applauders in their service and lend them to their friends. When Nero performed in the theatre his praises were chanted, at a given signal, by five thousand soldiers, who were called Augustals. The whole was conducted by a music-master, mesochorus or pausarius. It was this case of Nero which, occurring to the recollection of the French poet Dorat, may be said to have originated the well-known Paris claque. Buying up a number of the tickets for a performance of one of his plays, he distributed them gratuitously to those who pro mised to express approbation. From that time the claque, or organised body of professional applauders, has been a recognised institution in connection with the theatres of Paris. In the early ages of the Christian church it was by no means uncommon for an audience to express their appro bation of a favourite preacher during the course of his sermon. Chrysostom especially was very frequently inter rupted both by applause and by acclamations. In eccle siastical councils vote by acclamation is very common, the question being usually put in the form, placet or non jilacet. This differs from the acclamation with which in other assemblies a motion is said to be carried, when, no amend ment being proposed, approval is expressed by shouting such words as A ye or Agreed. ACCLIMATISATION is the process of adaptation by which animals and plants are gradually rendered capable of surviving and flourishing in countries remote from their original habitats, or under meteorological conditions dif ferent from those which they haTe usually to endure, and which are at first injurious to them. The subject of acclimatisation is very little understood, and some writers have even denied that it can ever take place. It is often confounded with domestication or with naturalisation ; but these are both very different pheno mena. A domesticated animal or a cultivated plant need not necessarily be acclimatised ; that is, it need not be capable of enduring the severity of the seasons without protection. The canary bird is domesticated but not acclimatised, and many of our most extensively cultivated plants are in the same category. A naturalised animal or plant, on the other hand, must be able to withstand all the vicissitudes of the seasons in its new home, and it may therefore be thought that it must have become acclimatised. But in many, perhaps most cases of naturalisation, there is no evidence of a gradual adaptation to new conditions which were at first injurious, and this is essential to the idea of acclimatisation. On the contrary, many species, in a new country and under somewhat different climatic conditions, seem to find a more congenial abode than in their native land, and at once flourish and increase in it to such an extent as often to exterminate the indigenous inhabitants. Thus Agassiz (in his work on Lake Superior) tells us that the road-side weeds of the north-eastern United States, to the number of 130 species, are all European, the native weeds having dis appeared westwards ; while in New Zealand there are, according to Mr T. Kirk (Transactions of the New Zealand Institute, vol. ii. p. 131), no less than 250 species of naturalised plants, more than 100 of which spread widely over the country, and often displace the native vegetation. Among animals, the European rat, goat, and pig, are naturalised in New Zealand, where they multiply to such an extent as to injure and probably exterminate many native productions. In neither of these cases is there any indication that acclimatisation was necessary or ever took place. On the other hand, the fact that an animal or plant cannot be naturalised is no proof that it is not acclimatised. It has been shown by Mr Darwin that, in the case of most animals and plants in a state of nature, the competition of other organisms is a far more efficient agency in limiting their distribution than the mere influence of climate. We have a proof of this in the fact that so few, comparatively, of our perfectly hardy garden plants ever run wild; and even the most persevering attempts to naturalise them usually fail. Alphonse de Candolle (Geographic Botanique, p. 798) informs us that several botanists of Paris, Geneva, and especially of Montpellier, have sown the seeds of many hundreds of species of exotic hardy plants, in what appeared to be the most favourable situations, but that in hardly a single case has any one of them become naturalised. Attempts have also been made to naturalise continental insects in this country, in places where the proper food- plants abound and the conditions seem generally favour able, but in no case do they seem to have sxicceeded. Even a plant like the potato, so largely cultivated and so perfectly hardy, has not established itself in a wild state in any part of Europe. Different Degrees of Climatal Adaptation in Animals and Plants. Plants differ greatly from animals in the closeness of their adaptation to meteorological conditions. Not only will most tropical plants refuse to live in a temperate climate, but many species are seriously injured by removal a few degrees of latitude beyond their natural limits. This is probably due to the fact, established by the experiments of M. Becquerel, that plants possess no proper temperature, but are wholly dependent on that of the surrounding medium. Animals, especially the higher forms, are much less sensitive to change of -temperature, as shown by the exten sive range from north to south of many species. Thus, the tiger ranges from the equator to northern Asia as far as the river Amour, and to the isothermal of 32 Fahr. The mountain sparrow (Passer montana) is abundant in Java and Singapore in a uniform equatorial climate, and also inhabits this country and a considerable portion of northern Europe. It is true that most terrestrial animals are restricted to countries not possessing a great range of temperature or very diversified climates, but there is reason to believe that this is due to quite a different set of causes, such as the presence of enemies or deficiency of appropriate food. When supplied with food and partially protected from enemies, they often show a wonderful capacity of enduring climates very different from that in which they originally flourished. Thus, the horse and the domestic fowl, both natives of very warm countries, nourish without special protection in almost every inhabited portion of the globe. The parrot tribe form one of the most pre-eminently tropical groups of birds, only a few species extending into the warmer temperate regions ; yet even the most exclu sively tropical genera are by no means delicate birds as regards climate. In the Annals and Magazine of Natural History for 1868 (p. 381) is a most interesting account, by Mr Charles Buxton, M.P., of the naturalisation of parrots
at Northreps Hall, Norfolk. A considerable number of
