In approaching the subject of the geographical distribution of animals and plants, one is struck with the marvellous methods which nature adopts for the dispersal of her types. If the seeds of forest trees were merely shed to the ground immediately beneath, they would be in an environment precisely the least likely to further the reproduction of their kind. Instead of this, many of the seeds of forest trees are furnished with wings, an adaptation which allows them to be easily wafted by the wind, and thus fits them for wide dispersal. It is only by possessing some such advantage as this that certain species could survive at all. It is true that acorns and other kindred fruits do not possess this advantage, but then they are largely fed upon by birds, and birds, as will presently be shown, are an admirable means of dispersal. The crop of a wood-pigeon, which burst when the bird fell to the ground when shot, was found to contain sixty-seven acorns, besides a number of beech mast and leaves of clover. In this connection imagine the possible rate of multiplication which would follow the accidental dissemination of a single head of red poppy. If left undisturbed it would, under ordinarily favourable circumstances, ripen forty thousand seeds, each capable of producing a successor. It has been stated by a competent authority that one red poppy could produce plants enough in less than seven years to occupy every inch of the thirty and odd million acres of the United Kingdom. Ocean currents have not unfrequently been the means of connecting the floras of different continents, and seeds and fruit are sometimes picked up on the western coasts of Britain which have been wafted across the whole Atlantic Ocean. It is also known that certain birds of long and sustained powers of flight cross the Atlantic unaided, and what this may possibly mean will presently be shown. Even land animals are known to cross straits between island and island upon rafts--drift-wood or bits of floating bark.