CLEWS IN NATURAL HISTORY. 



17 



some multiple of that number) in the pistil. Where there appears to 

 be a lack of this numerical correspondence, the botanist concludes that 

 some violation of the law of symmetry has taken place, and that some 

 parts or organs which should normally have been developed have been 

 altered or suppressed. His reasoning, in fact, proceeds on the plain basis 

 of first establishing, through experience, the normal number and con- 

 dition of parts in the flower of any given order of plants, and of there- 

 after accounting by suppression or non-development for the absence of 

 parts he expected to have been represented. 



Now, in the snapdragon tribe, we find, as a general rule, five parts 

 in the calyx, five petals in the corolla, but only four stamens. Such a 

 condition of matters is well seen in the flower of frog's-mouth {Antir- 

 rhinum), where we find four stamens, two being long and two short 

 (Fig 2, A s 1 s 2 ), as the complement of the 

 flower. We account for the absence of a 

 fifth stamen by saving it is abortive. But 

 a natural reflection arises at this point, 

 in the form of the query, Have we any 

 means of ascertaining if our expectation 

 that a fifth stamen should be developed is 

 rational and well founded? May not the 

 plant, in other words, have been " created 

 so ? " Fortunately for science, Nature 

 gives us a clew to the discovery of the 

 truth in this as in many other cases. In 

 one genus of these plants (Scrophularia), we find a rudiment of a fifth 

 stamen (Fig. 2, Bs), and in snapdragon itself this fifth stamen becomes 

 occasionally fully developed ; while another plant of the order (Mullein) 

 possesses five stamens as its constant provision. Unless, therefore, we 

 are to maintain that Nature is capricious beyond our utmost belief, we 

 are rationally bound to believe that the rudimentary fifth stamen of 

 ScrophitlaHa, and the absent fifth stamen of other plants of its order, 

 present us with an example of modification and suppression respectively. 

 The now rudimentary stamen is the representative of an organ once 

 perfect and fully developed in these flowers, and which it perpetuated 

 by the natural law of inheritance until conditions, to be hereafter no- 

 ticed, shall have caused it to entirely disappear. The case for the natu- 

 ral modification, and that against the imperfect creation of such flowers, 

 is proved by an ingenious experiment of Kolreuter's, upon plants which 

 have the stamens and pistils situated in different plants, instead of be- 

 ing contained in the same flower, as is ordinarily the case. Some stam- 

 inate or stamen-possessing flowers had the merest rudiment of the pistil 

 developed, while another set had a well-developed pistil. When these 

 two species were "crossed" in their cultivation, the "hybrids" or mule 

 progeny thus produced evinced a marked increase in the development 

 of the abortive organ. This experiment not only proved that, under 



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Fig. 2. 



