80 OBSERVATIONS ON FLORAL CHANGES. 



causing the entire destruction of many animals. The larger carnivorous species 

 give way before us, but other quadrupeds of smaller size, and innumerable 

 birds, insects, and plants, which are inimical to our interests, increase in spite 

 of us, some attacking our food, others our raiment and persons, and others 

 interfering with our agricultural and horticultural labours. We force the ox 

 and the horse to labour for our advantage, and we deprive the bee of his 

 store; but, on the other hand, we raise the rich harvest with the sweat of 

 our brow, and behold it devoured by myriads of insects, and we are often as 

 incapable of arresting their depredations, as of staying the shock of an earth- 

 quake, or the course of a stream of burning lava. The changes caused by 

 other species, as they gi'adually diffuse themselves over the globe, are inferior 

 probably, in magnitude, but are yet extremely analogous to those which we 

 occasion. The lion, for example, and the migratory locust, 'must necessarily, 

 when they first made their way into districts now occupied by them, have 

 committed immense havoc amongst the animals and plants which became their 

 prey. They may have caused many species to diminish, perhaps wholly to 

 disappear; but they must also have enabled some others greatly to augment 

 in number, by removing the natural enemies by which they had been previously 

 kept down. It is probable from these and many other considerations, that as 

 we enlarge our knowledge of the system, we shall become more and more 

 convinced, that the alterations caused by the interference of man, deviate far 

 less from the analogy of those effected by other animals than we usually 

 suppose. We are often misled, when we institute such comparisons, by our 

 knowledge of the wide distinction between the instincts of animals, and the 

 reasoning power of man; and we are apt hastily to infer, that the effects of 

 a rational and an irrational species, considered merely as physical arjents, will 

 differ almost as much as the faculties by which their actions are directed. 

 A great philosopher has observed, that we can only command nature by 

 obeying her laws, and this principle is true, even in regard to the astonishing 

 changes which are superinduced in the qualities of certain animals and plants, 

 by domestication and garden culture. We can only effect such surprising 

 alterations by assisting the development of certain instincts, or by availing 

 ourselves of that mysterious law of their organization, by which individual 

 peculiarities, are transmissible from one generation to another." The dis- 

 tinctness, however, of the human from all other species, considered merely 

 as an efficient cause in the physical world, is real, for we stand in a 

 relation to contemporary species of animals and plants, widely different from 

 that which irrational animals can ever be supposed to have held to each 

 other. We modify their instincts, relative numbers, and geographical distri- 

 bution in a manner superior in degree, and, in some respects, very different in 

 kind from that in which any other species can affect the rest." 



Mr. Landsborough, in his delightful treatise on sea-weeds, puts forth an 

 apology for naturalized plants; in treating of the two species of Sargassum, 

 he suys, "they have no just claim to take rank in our British Flora. But 



