NOTICES OF BOOKS. ' 12l 



invariably retain their peculiarities from generation to generation, both 

 when propagated by seed and, more markedly still, when increased 

 otherwise). As it is often impossible to tell what should be consi- 

 dered a race, and what a species, the existence of races may perhaps 

 be assumed to present an insuperable obstacle to the determination of 

 the limits of many species. Jt may take years to prove that a variety 

 is nothing more than a variety ; but it is obviously hopeless, in most 

 cases, to expect to prove that a race is only a more permanent kind 

 of variety. Recourse must be had to hybridizing, which however is 

 not now held to be an absolute test. Analogy with other plants must 

 also be appealed to ; but the acknowledged fact that characters which 

 are held to be of no more rank than variations in some plants, are of 

 specific value in others, often renders this line of argument useless. 



Under the head of changes that may be effected in species by causes 

 protracted through many ages, or many thousands of years preceding 

 the present, the subject of acclimatation is discussed. Accliraatation 

 M. de CandoUe holds (with Petit-Thouars and others) to be a chimera ; 

 plants either resist the eifects of altered conditions and flourish, or 

 succumb under them ; they, do not change their natures. On the 

 other hand, he admits the existence of wild races of plants just as of 

 cultivated races. 



(7b he continued.) 



w 



The Art of Per- 



of oMaining tJie Odours of 



for the manufacture of Perfumes, etc, 12rao. London. 



1855. With 



Among the varied products of vegetables the '' odours " have been 

 justly and universally celebrated in prose and in verse, and our author 

 introduces, at the opening of his first Chapter, Thomson's well-kziown 

 and appropriate lines : 



€t 



VOL. VTTI. 



By nature's swift and secret working hand 

 The garden glows, and fiUa the liberal air 



With lavish odouTB. 



There let me draw 



Ethereal soul, there drink reviving gales, 

 Profusely breathing from the spicy giwcs 

 And vales of fragrance." 



K 



