certain conditions, the rudimentary pistil could be improved and bettered, but also the identity of the two pistils, and the high probability that the abortive organ in the one flower was simply the degraded representative 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 wallflower 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 multiple 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 2) 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 matters 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 conditions 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 become degraded when they are no longer found to be useful to the economy 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