Let us first consider the main mass of our flora, which is closely akin to that of the adjoining parts of the Continent. When we say that it represents a reduced Continental flora we do not imply that it is therefore uniform in its composition throughout the British Isles. We know, on the contrary, by everyday observation, that it varies much in its constituents. The principal general change is noticed if one travels from the south of England to the north of Scotland. Great Britain extends in this direction for 700 miles--far enough to allow climate to have a marked effect as between its extremities. The flora of Hampshire is very different from that of Caithness or the Orkneys. But both represent in the main the vegetation of that part of the Continent which lies in the same latitude, the Hampshire flora being akin to that of Northern France, the Caithness flora to that of Southern Scandinavia. The likeness is in each case heightened by the fact that the rocks of the respective areas correspond, producing similar soils, which tend to support similar floras. The soft Secondary and Tertiary deposits of Southern England are repeated in the Paris basin and surrounding area, while the ancient gneisses of Scotland are akin to those of Norway. To quote a few instances of this north and south difference coupled with east and west similarity: the Small-flowered Crowfoot (_Ranunculus parviflorus_), White Bryony (_Bryonia dioica_), Water Violet (_Hottonia palustris_), Yellow-wort (_Blackstonia perfoliata_), and Black Bryony (_Tamus communis_), all widely spread throughout England and Wales, die out in or about the Lake District, and are absent from Scotland; the Scale Fern (_Ceterach officinarum_) gets farther north--about half-way up Scotland--before it disappears; other plants again, widespread in the south, die out before the Mersey-Humber line, or even the Severn-Thames line, is crossed. On the Continent, the plants enumerated are mainly southern in their range. All occur widely in Central and Southern Europe, but from Scandinavia most are absent, and the rest are rare. On the other hand, some characteristic Scottish species cease as we come southward--the little _Primula scotica_, for instance, is confined to the northern extremity of Scotland; the Chickweed Wintergreen (_Trientalis europæa_) ranges only as far south as Yorkshire; and the beautiful Globe Flower (_Trollius europæus_), so characteristic of northern pastures, creeps southward as far as the Severn. The first of these is on the Continent confined to Scandinavia; the others, though found in France, etc., are characteristic of the hilly regions there, and are much more abundant farther northward.