376 ON THE ORIGIN OF SPECIES 



characters proper to the species, to the genus, to the 

 family, to the class, disappear, and thus laugh at our 

 classification.' But when Aspicarpa produced in France, 

 during several years, only degraded flowers, departing 

 so wonderfully in a number of the most important 

 points of structure from the proper type of the order, 

 yet M. Richard sagaciously saw, as Jussieu observes, 

 that this genus should still be retained amongst the 

 Malpighiaceae. This case seems to me well to illustrate 

 the spirit with which our classifications are sometimes 

 necessarily founded. 



Practically when naturalists are at work, they do 

 not trouble themselves about the physiological value 

 of the characters which they use in defining a group, 

 or in allocating any particular species. If they find 

 a character nearly uniform, and common to a great 

 number of forms, and not common to others, they use 

 it as one of high value ; if common to some lesser 

 number, they use it as of subordinate value. This 

 principle has been broadly confessed by some naturalists 

 to be the true one ; and by none more clearly than by 

 that excellent botanist, Aug. St. Hilaire. If certain 

 characters are always found correlated with others, 

 though no apparent bond of connection can be dis- 

 covered between them, especial value is set on them. 

 As in most groups of animals, important organs, such as 

 those for propelling the blood, or for aerating it, or those 

 for propagating the race, are found nearly uniform, they 

 are considered as highly serviceable in classification ; 

 but in some groups of animals all these, the most im- 

 portant vital organs, are found to offer characters of 

 quite subordinate value. 



We can see why characters derived from the embryo 

 should be of equal importance with those derived from 

 the adult, for our classifications of course include all 

 ages of each species. But it is by no means obvious, 

 on the ordinary view, why the structure of the embryo 

 should be more important for this purpose than that of 

 the adult, which alone plays its full part in the economy 

 of nature. Yet it has been strongly urged by those 



