HOOKER AND THOMSON'S INDIAN FLORA. 63 



want on the part of many naturalists of clear and logical 

 views in respect to classification and system ; — " the prevail- 

 ing tendency on the part of students of all branches of nat- 

 ural history to exaggerate the number of species, and to 

 separate accidental forms by trifling characters ; " — the un- 

 philosophical and detrimental character of " the modern sys- 

 tem of elevating every minor group, however trifling the 

 peculiarities by which it is distinguished, to the rank of a 

 genus ; " in other words, of considering every group of species 

 to form a genus, — evincing a want of appreciation of the true 

 value and nature of classification ; — the fact that in the vege- 

 table kingdom we do not discover that close and obvious con- 

 nection between structure and function which is almost uni- 

 versally apparent in the animal kingdom, giving to physiol- 

 ogy a greater influence over classification in zoology than in 

 botany, and offering a guide to determining the relative value 

 of structural characters in the one kingdom which is com- 

 paratively little available in the other, but yet may not safely 

 be neglected. 



Our authors assume, as most accordant with known facts 

 on the whole, that species are distinct creations, and not arbi- 

 trary assumptions of the systematists ; and they adopt that 

 idea of species which alone appears to give them a perfectly 

 clear and intelligible, distinct, objective existence in nature, 

 namely, that they consist of individuals which have originated 

 each from a common stock. They assume not only their 

 original, but their continued definiteness in nature ; but their 

 variations, surprising as they often are, are restricted within 

 certain limits, to which we may add that these limits are not 

 a priori determinable. Among the causes inducing variation, 

 or tending to produce a blended series of individual forms, if 

 such did not exist from the beginning, they first consider the 

 effects of hybridization ; and remark that recent experiments 

 have led to the following results : 



" 1. It is a much more difficult operation to produce hy- 

 brids, even under every advantage, than is usually supposed. 

 The number of species capable of being impregnated, even by 

 skillful management, is very few ; and in nature the stigma 



