CiiAP. .\III. CLASSIFICATION. 377 



characters ; for this seems foun Jed on an .appreciation of many 

 trillinp;' points of resemblance, too slif^ht to be delinetl. Cer- 

 tain plants, belongiiii^ to the Mali)igliiacene, bear perfect and 

 degraded fio\vcrs; in the hitter, as A. do Jussicuhas remarked, 

 " the grc'iter nuinl)er of the characters proper to the species, 

 to the genus, to tlie 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 among the MalpighiacefO. This case seems to 

 me well to illustrate the spirit of our classification. 



Practically, Avhen naturalists are at work, they do not 

 trouble themselves about the physiological value of the charac- 

 ters 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 prin- 

 ciple 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 con- 

 nection can be discovered between them, especial value is set 

 on them. As in most groups of animals, important organs, 

 such as those fc^r propelling the blood, or for aerating it, or 

 those for propagating the race, arc foimd nearly uniform, they 

 are considered as highly sernceable in classification; but in 

 some groups of anim:ds all these, the most important vital 

 organs, are found to ofler characters of quite subordinate value. 

 Thus, as Fritz MllUer has lately remarked, in the same group 

 of crustaceans, ('ypridina is furnished Avith a heart, while in 

 two closely-allied genera, namely, C^-pris and Cytherea, there 

 is no such organ : one species of Cypridina has well-developed 

 branchi.'C, while another species is destitute of them. 



Wo can see why characters derived from the embrj^o should 

 be of equal importance with those derived from the adult, for 

 a natural classification of course includes all ages. But it is 

 by no means ol)vious, 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 econo- 

 my of Nature. Yet it has been strongly urged by those great 



