32 ZOOLOGICAL PHILOSOPHY 



alone are of importance in deciding affinities, I should set forth these 

 parts in their order of importance as follows : 



(1) The embryo, its accessories (cotyledons, perisperm) and the 

 seed which contains it. 



(2) The sexual parts of flowers, such as the pistil and stamens. 



(3) The envelopes of the sexual parts ; the corolla, calyx, etc. 



(4) The pericarp, or envelope of the seed. 



(5) The reproductive bodies which do not require fertilisation. 

 These generally received principles give to natural science a coherence 



and solidity that it did not previously possess. Affinities are no longer 

 at the mercy of changes of opinion ; our general classifications become 

 necessary inferences ; and according as we perfect them by this 

 method they approach ever more closely to the actual order of 

 nature. 



It was, in fact, due to the perception of the importance of affinities that 

 the attempts of the last few years were originated to determine what 

 is called the natural method ; a method which is only a tracing by 

 man of nature's procedure in bringing her productions into existence. 



No importance is now attached in France to those artificial systems 

 which ignore the natural affinities among objects ; for these systems 

 give rise to divisions and classifications harmful to the progress of 

 natural knowledge. 



With regard to animals, there is no longer any doubt that it is purely 

 from their organisation that their natural affinities can be determined. 

 It is, in consequence, chiefly from comparative anatomy that zoology 

 will obtain the data for such determination. But we should pay 

 more attention to the facts collected in the works of anatomists than 

 to the inferences which they draw from them ; for too often they hold 

 views which might mislead us and prevent us from grasping the 

 laws and true plan of nature. It seems to be the case that whenever 

 man observes any new fact he is always condemned to rush headlong 

 into error in attempting to explain it ; so fertile is his imagination 

 in the creation of ideas. He is not sufficiently careful to guide his 

 judgment by the general principles derived from other facts and 

 observations. 



When we consider the natural affinities between objects, and make 

 a sound estimate of them, we can combine species on this principle, 

 and associate groups with definite boundaries forming what are 

 called genera. Genera can be similarly associated on the principle of 

 affinities, and united into higher groups forming what are called 

 families. These families, associated in the same way and on the same 

 principle, make up orders. These again are the primary divisions of 

 classes, while classes are the chief divisions of each kingdom. 



