16 



THE POPULAR SCIENCE MONTHLY. 



planation thus afforded of the nature and origin of these disused parts 

 is endorsed by the fuller knowledge of their history ; while, from a 

 study apparently of insignificant interest, may be shown how certain of 

 our living neighbors, along with ourselves, have, from lower states, and 

 from the dawning epochs of the world, literally taken their place " in 

 the foremost files of time." 



As most persons who have attentively looked at any common plant 

 can tell, four parts are included in a perfect flower. These parts or sets 



Fig. l. 



of organs, as seen in the wallflower, consist (Fig. 1), firstly, of an outer 

 covering colored green, and named the " calyx " (ca). Then comes the 

 blossom or flower itself, forming the "corolla" (co). Inside the corolla 

 we find certain stalked organs, each bearing a little head or " anther," 

 filled with a yellow dust, the " pollen." These organs are the " stamens " 

 (st). Lastly, in the center of the flower, we note the "pistil" (p), or 

 organ devoted to the production of " ovules." The latter, when duly 

 fertilized by being brought into contact with the " pollen " of the sta- 

 mens, become " seeds," and are capable of growing up, when planted, 

 into new plants. Now, the botanist will inform us that it is a matter 

 of common experience to find some individual plants of a species with 

 well-developed petals or blossoms, and other individuals of the same 

 species with petals in a rudimentary condition, thus proving that the 

 production of imperfect parts in flowers occurs as an ordinary event 

 under our own eyes, and under the common conditions of plant-life. 

 The natural order of plants to which snapdragon belongs presents a 

 peculiarity, inasmuch as in most of its members one of the five stamens 

 is abortive or rudimentary. It should be borne in mind that the botan- 

 ist possesses a highly interesting and exact method of ascertaining how 

 many parts or organs should be represented in plants. He places his 

 reliance in this respect on the working of what may be called the " law 

 of symmetry." The operation of this law, which may be said to be 

 founded on wide experience, tends to produce a correspondence in 

 numbers between the parts in the four sets of organs of which we have 

 just noted a flower to be composed. Thus, when we count five parts in 

 the green calyx of a plant, we expect to find five blossoms or petals in 

 its corolla; five stamens (or some multiple of five) and five parts (or 



