NATURAL CLASSIFICATION. 183 



combined into an Order on account of the agreement in the structure of 

 the ovary and its relations to the floral envelopes. The characters of seeds, 

 and more particularly of the embryos, give a still higher divisional cha- 

 racter. These characters of successively higher groups are marked in 

 organs of progressively higher physiological and morphological impor- 

 tance, affinities between such organs being proportionately more valuable. 

 But they possess this value not merely on their own account ; for if that 

 were the case, the method would be still to a great extent artificial : they 

 indicate the coexistence of proportionate agreement in the total organi- 

 zation, which renders them exponents not merely of the affinities of the 

 plants in respect to the particular structure to which they belong, but of 

 all their affinities, and of the rank which a given plant holds in the 

 Vegetable Kingdom. As a general rule, it is found that the agreement 

 of the total organization of plants is generally proportionate to the phy- 

 siological value of any given organs in which they agree ; or, in other 

 words, agreement in the structure of any given organ indicates general 

 agreement in all the organs of less importance than itself. The agreement 

 here referred to is of course a general structural agreement, a relation to 

 a common type not a resemblance excluding the multifold minor diver- 

 sities which present themselves within the limits of almost every type. 



Practically, moreover, we have another principle to keep in view, 

 which indeed, while it affords as it were the verification of the in- 

 ductions of the above principle, is our sole guide in dealing with 

 the subdivisions of the more comprehensive types. This is the rule 

 that the closest affinities are marked by the agreement in the majo- 

 rity of characters of eqtlal importance ; or if the characters, as is 

 more commonly the case, are of unequal importance, the principle 

 of decision by the majority is carried out by ascertaining the pro- 

 portionate values of the organs in which agreements and differences 

 exist, and striking a balance as with equal factors. 



Many of the older botanists had attempted to construct a Natural Sys- 

 tem ; and Linnaeus left a sketch or fragment of one, in the form of a list 

 of names of families without definitions, regarding its realization as the 

 ultimate aim of Botany. Many of the families in these older Systems are 

 grounded almost exclusively on " habit," or general external character. 

 The two Jussieus, Bernard and Antoine-Laurent, have the merit of the 

 discovery of the only principles upon which a really Natural System can 

 be founded. And so accurately did A.-L. de Jussieu carry out these prin- 

 ciples in his arrangement of the then existing genera, that the families 

 which he established are still almost all received into our present Systems, 

 where some of them are indeed broken up into smaller groups, but where 

 the greatest increase in the number of families arises from subsequent 

 discoveries. 



The characters of the natural Families established in this way will be 

 found to be far less exact and definite than those of the Linnsean classes and 

 orders, and by no means so rigid even as those of natural genera. The cha- 

 racter of a family is founded on the totality of its essential characters, and 

 includes the essential characters of agreement of all its genera. The genera 

 contained in most of the families exhibit a considerable range of differences j 



