BOTANY and E. G. Varenne is sufficient guarantee of the trustworthiness of those records. There is no reason to suppose that the flora of the county has changed since the publication of Gibson's Flora. I have botanized through that portion of the county which forms Gibson's district 8, Mr. E. E. Turner of Witham has done much work in district 7, and the Rev. J. T. Powell has contributed a paper to the Essex Naturalist (vi. i) on the existing flora of Epping Forest. I do not know of any species of flowering plants which have been certainly lost to us. Ft/ago gallica has not been found for some years, owing to the field from which it was formerly collected having been left uncultivated. In some districts of the county, more especially near the metro- polis, the rapid growth of town threatens the early destruction of the flora. Such abundant plants as the primrose and the wild hyacinth are said to have been almost exterminated in some neighbourhoods, and the advent of the bicycle has unfortunately extended the range through which this destruction may take place. DISTRIBUTION
The chief forces which influence the distribution of plants may be generalized as follows. When we travel north and south we observe considerable change in the flora, and though such changes are not very marked in a small country like England, the distinction between the flora of the tropical, subtropical, temperate and arctic latitudes has always greatly impressed travellers. Again, as we travel east and west a less marked change may be noted. In the latter case the difference in the climatic conditions is not great. In so small an area as that of Essex these changes may be neglected. When we climb a mountain, plants which were abundant at the lower levels gradually disappear and new ones take their place. The highest ground in Essex does not greatly exceed 400 feet above the sea ; we should therefore not expect to meet with representatives of the mountain flora, but strange though it may seem our coast produces several plants which are also found high up on mountains, though they do not grow at intervening altitudes. The most potent agent in regulating the distribution of plants is undoubtedly climate. The difference between tropical, subtropical, temperate and arctic vegetation is so marked that geologists do not hesitate to tell us that England was once a tropical and later an arctic country, because they find remains of tropical and arctic flora in different strata underlying our eastern counties. England was once part of the continent of Europe, and during at least a portion of that time was clothed by arctic plants ; these however gave place to our modern flora, which is similar in character to the flora of Europe, and is therefore no doubt derived from the adjacent continent. i 33 5
