18 THE POPULAR SCIENCE MONTHLY. 



certain conditions, the rudimentary pistil could be improved and bet- 

 tered, but also the identity of the two pistils, and the high probability 

 that the abortive organ in the one flower was simply the degraded rep- 

 resentative of the well-developed part of the other. 



As a final example of the manner in which we receive clews toward 

 the explanation of the modifications of flowers, the case of the wall- 

 flower is somewhat interesting. This plant and its neighbors possess 

 the parts of the flower in fours. (Fig. 1, A.) There are four sepals and 

 four petals, while six stamens (Fig. 1, B) are developed ; the pistil 

 possessing only two parts. Here the law of symmetry would lead us 

 to expect either four stamens or eight the latter number being a mul- 

 tiple of four. The clew to this modification is found in the arrangement 

 of the stamens. We find that four of the wallflower's stamens are 

 long (Fig. B, st '), while two (st a ) are short. The four stamens form 

 a regular inner series or circle, the two short stamens being placed, in 

 a somewhat solitary fashion, outside the others. This condition of mat- 

 ters clearly points to the suppression of two of an originally complete 

 outer row of four stamens, and we receive a clew as to the probability 

 of this view by finding that in some other flowers of the wallflower's 

 group the stamens may be numerous. It is hardly within the scope of 

 the present article to say anything regarding the causes of the condi- 

 tions or of the agencies through which the modifications of plants are 

 wrought out. Suffice it to remark that the " law of use and disuse " of 

 organs explains the majority of such cases, by asserting that organs be- 

 come degraded when they are no longer found to be useful to the econ- 

 omy of their possessors. The degradation of a part is to be looked 

 upon as subservient to the welfare of the animal or plant as a whole, 

 and thus comes to be related to the great law of adaptation in nature 

 which practically ordains that 



Whatever is, is right. 



The animal world presents us, however, with more obvious and bet- 

 ter-marked examples of rudimentary organs than are exhibited by the 

 modifications of flowers conspicuous as many of these latter instances 

 undoubtedly are. Turning our attention first to lower life, we find 

 among insects some notable and instructive illustrations of abortive 

 organs, and also of the ways and means through which the rudimentary 

 conditions have been attained. In the beetle order, the natural or com- 

 mon condition of the wings which in insects typically number four 

 is that whereby the first pair becomes converted into hardened wing- 

 cases, beneath which the hinder and useful wings are concealed when 

 at rest. Now, in some species of beetles, we may meet with certain 

 individuals with normally developed wings ; while in other individuals 

 of the species we find the wings to be represented by the merest rudi- 

 ments, which lie concealed beneath wing-cases, the latter being actually 

 firmly and permanently united together. In such a case the modifies- 



