344 CLASSIFICATION. [ CHAP - X1V - 



Again, no one will say that rudimentary or atrophied organs are 

 of high physiological or vital importance ; yet, undoubtedly, 

 organs in this condition are often of much value in classification. 

 No one will dispute that the rudimentary teeth in the upper jaws 

 of young ruminants, and certain rudimentary bones of the leg, are 

 highly serviceable in exhibiting the close affinity between rumi- 

 nants and pachyderms. Robert Brown has strongly insisted on 

 the fact that the position of the rudimentary florets is of the 

 highest importance in the classification of the grasses. 



Numerous instances could be given of characters derived from 

 parts which must be considered of very trifling physiological 

 importance, but which are universally admitted as highly service- 

 able in the definition of whole groups. For instance, whether or 

 not there is an open passage from the nostrils to the mouth, the 

 only character, according to Owen, which absolutely distinguishes 

 fishes and reptiles the inflection of the angle of the lower jaw in 

 Marsupials the manner in which the wings of insects are folded 

 mere colour in certain Algae mere pubescence on parts of the 

 flower in grasses the nature of the dermal covering, as hair or 

 feathers, in the Vertebrata. If the Ornithorhynchus had been 

 covered with feathers instead of hair, this external and trifling 

 character would have been considered by naturalists as an im- 

 portant aid in determining the degree of affinity of this strange 

 creature to birds. 



The importance, for classification, of trifling characters, mainly 

 depends on their being correlated with many other characters of 

 more or less importance. The value indeed of an aggregate of 

 characters is very evident in natural history. Hence, as has often 

 been remarked, a species may depart from its allies in several 

 characters, both of high physiological importance, and of almost 

 universal prevalence, and yet leave us in no doubt where it should 

 be ranked. Hence, also, it has been found that a classification 

 founded on any single character, however important that may be, 

 has always failed ; for no part of the organisation is invariably 

 constant. The importance of an aggregate of characters, even 

 when none are important, alone explains the aphorism enunciated 

 by Linnaeus, namely, that the characters do not give the genus, 

 but the genus gives the characters ; for this seems founded on the 

 appreciation of many trifling points of resemblance, too slight to 

 be defined. Certain plants, belonging to the Malpighiaceae, bear 

 perfect and degraded flowers ; in the latter, as A. de Jussieu has 

 remarked, " the greater number of the characters proper to the 

 species, to the genus, to the family, to the class, disappear, and 

 thus laugh at our classification." When Aspicarpa produced in 

 France, during several years, only these degraded flowers, depart- 

 ing so wonderfully in a number of the most important points of 



