The influence of climate in modifying the characters of plants is a circumstance known to all botanical students. The same plant, in temperate regions and under the tropics, exhibits different properties, or, we should rather say, in one instance developes more highly certain properties which in the other lie nearly dormant. The newly-introduced sorghum, from which we have been promised an unfailing supply of excellent sugar, fails in the North of France to reach that degree of maturity, or to develope in such manner its saccharine secretions as to be available for the manufacture of a crystallizable sugar. The sweet floating grass (_Glyceria fluitans_) in Poland and Russia supplies farinaceous seeds, which, under the name of manna croup, are consumed as food; but no seeds at all available for that purpose are produced at home from the same plant, although it grows freely. The flavour of the onion, as grown in Egypt, is, we are assured, far milder, and vastly different from the bulbs cultivated in Britain. The odour of violets and other flowers grown for perfumery and other purposes at Nice, have a scent more rich and delicious than when grown in English soil, subject to our variable climate. But the most extraordinary effect of all, produced by these influences upon plants, occurs in the case of hemp, which in Europe developes its fibrous qualities to such an extent as to produce a material for cordage hitherto unsurpassed; but in India, while deficient in this respect, developes narcotic secretions to such an extent as to occupy a prominent position among the chief narcotics of the world. It was for some time supposed that the Indian or narcotic hemp was a different species to that which is cultivated for textile purposes; and even now it is often characterised by a different specific name, which would seem to assume that the species are distinct. This, however, the most celebrated of our botanists deny. The difference is declared to be, not one of species, but of climate, and of climate only. The native home of the hemp plant is assigned by Dr. Lindley to Persia and the hills in the North of India, whence it has been introduced into other countries. Burnett says, “Hemp seed is nutritious and not narcotic; it has the very singular property of changing the plumage of bullfinches and goldfinches from red and yellow to black, if they are fed on it for too long a time or in too large a quantity.” Never having tried the experiment, we have no ground for disputing or authority for verifying these remarks. If such, however, is the case, hemp seed possesses some property, if not narcotic, which canary and poppy seeds, we should presume, do not.