8 PRELIMINARY INQUIRIES. 



observations of the late Dr. Turner, " that when mineral matter is in a ' nascent state,' that is to 

 say, just liberated from a previous state of chemical combination, it is most ready to unite with other 

 matter, and form a new chemical compound."* In other words, inertia once destroyed, and motion 

 given, impulse is more readily received and propagated. The ordinary state of quiescence will 

 bo resumed as soon as the animal has become habituated to the alteration ; but by that time it 

 is no longer the same animal, it has become a new species. In this way, and in this way only, 

 do I think that hybridization may have some influence in producing a new species, viz., by disturbing 

 the normal stability of an earlier species, and preparing it to receive an impulse from less alteration 

 of condition than would otherwise have affected it. 



It may be objected to this hypothesis, that it is inconsistent with our experience of exotic 

 plants which have been naturalized in this country. We have plenty of plants which have been 

 brought from the other side of the world, and have been grown for a couple of hundred years in 

 this coimtry, and yet no alteration is perceptible iqjon them. My answer to this is, tliat one essential 

 element in my theory is, that the change is effected through the medium not of single individuals, 

 but of a midtitude of individuals — a whole nation of the same species ; and I know of no instance 

 in which such an agglomeration of exotic species has ever existed in this country. We can easily 

 conceive that where the individuals are isolated or in small numbers, any change wliich might 

 show itself uj)on one or two of their descendants may have escaped our observation, and become 

 extinguished before it was established for want of individuals through which to prof)agate, develops, 

 and extend it. Moreover, the process of change is obviously gradual and imperceptible, and extends 

 over a greater space of time than we have had the opportunity of obser^'ing. 



Again, the sj)ccies may have been of those possessing constitutions adapted to admit without 

 feeling them considerable variation in their conditions of life ; and lastly, it is not absolutely true 

 that no change has been observed ; our observations in this country are made on plants or animals 

 which are soon killed by the climate, if the conditions of life are not pretty well suited to their 

 constitution. Where the climate is warmer, it seems that a greater change of condition can be 

 borne than in cold countries without killing the species ; and in tropical lands a change is cer- 

 tainly observed. In cattle, the Pelones and Calougas now existing in the warmer and warmest 

 parts respectively of South America, having been changed from ordinary cattle so much that the 

 former has only very fine short hair, and the latter no hair at all. The effect of climate on the 

 wool of sheep is well known ; and Mr. Winwood Rcade, in speaking of the different animals and 

 plants introduced into West Africa, speaks of a nmrkcd change in all. The horse rapidly deteriorates, 

 and in some jjlaces cannot be kept alive at all. The shecjj change in other respects than their 

 wool ; the very dogs, which we shovdd expect to bear the change at least as well as their masters, 

 alter under the baleful climate. " In process of time," writes Bosman, " our dogs alter strangely 

 here ; their ears grow long and stiff like those of foxes, to which colour they also incline, so that 

 in three or four years they degenerate into very ugly creatures ; and in three or four broods their 

 barking turns into a howl." As to plants Mr. Reade says, " It is only on the borders of malarious 

 Africa, that is to say, in Angola and Sonegambia, that most foreign j)lan(s and vegetables can be 

 made to live ; and these, as Mr. Gabriel of Loanda informed me, completely changed their nature 

 when planted in the African soil."f 



liut althougli I mention these instances, it is not on them that I relv for an answer to the 



* Lyei-l's " Elements of Geology." Si.\th edition, 18G5, p. 41. t Ekade, Wikwood, " Savage Africa," 1863, p. 519. 



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