338 THE POPULAR SCIENCE MONTHLY. 



seed. Dr. Gray lias likened the plant to the fabled phoenix, which, 

 consuming itself in giving birth to its offspring, literally rises 

 from its ashes. 



All the parts of a complete and perfect flower are, morphologi- 

 cally speaking, modified leaves. It can often be observed that 

 true leaves pass insensibly into bracts. These in turn pass into 

 sepals, and these again into petals. Sepals, being as a rule green, 

 can be more easily seen to be modified leaves than petals. The 

 last are usually colored, and the fact is not so noticeable. Yet, in 

 the flowers of the cacti, the line between the outer bracts and the 

 sepals, and between these and the petals, can not be drawn, for 

 they pass imperceptibly into each other. In the Nymphwa 

 (water-lily) there are numerous rows of petals, and a gradual 

 change can be traced from the outer row of petals into stamens. 

 First at the tip of a petal are developed two small lobes, one on 

 each side. These lobes enlarge as the center of the flower is 

 reached, and at last a fully formed anther at the top of a slender 

 filament is the result. All the various stages through which the 

 stamen has passed are visible in the rows of petals. 



According to Mr. Grant Allen, the original and primitive flow- 

 ers were made up of stamens and pistils only as the essential 

 organs of the flower ; and the petals and sepals are but stamens 

 modified by insect agency. Now, whether petals are regarded as 

 modified stamens or stamens as modified petals is immaterial. 

 There is nothing to prevent the adoption of both views. The 

 stamens must, in the first place, have been leaves ; for it often 

 happens that ordinary leaves are found bearing pollen grains on 

 their edges. So, too, the anther is to be regarded as the modified 

 apex of a rolled-up leaf. As the flowers became, in the course of 

 time, more and more suited to insects, some of the stamens were 

 doubtless changed back into leaves in the shape of petals and 

 sepals, while at the same time the true leaves of the stem may 

 have been changed into bracts of various sorts. 



There will be noticed, on the examination of any ordinary 

 stamen, two principal parts. One is the long, slender stalk or fila- 

 ment, and the other is the knob at the end, or the anther. The 

 filament, says Sachs, is to be regarded as the staminal leaf. The 

 anther is made up of two lobes, situated at or near the apex of the 

 filament, one on each side, and separated by a prolongation of the 

 filament known as the connectile. In these two lobes the pollen 

 is developed. Sachs says that "the formation of . . . the pollen 

 grains of phanerogams always takes place by the division of the 

 mother-cell into four parts." This division takes place as fol- 

 lows : In the process of growth of the original mother-cell, the 

 nucleus becomes divided into two parts, each soon forming the 

 center of a new cell. These two again each divide and finally 



