344 



KNOWLEDGE & SCIENTIFIC NEWS. 



[February, 1906. 



The Evolvition of the 

 Flower. 



By S. Leonard Bastin. 



(Continued from page 324.) 



PART II. 



The conspicuous and often attractively coloured sepals 



and petals of the flower, whilst servinor their special 



purpose, are, after all, of but small importance when 



they may be all joined together. Each carpel terminates 

 in a longish pillar called a style, at the summit of which 

 is the stigma, a moist, fleshy surface to which the 

 grains of pollen readily adhere, .^t the base of the 

 carpel is to be found the ovule, that highly specialised 

 organ which is the forerunner of the seed. 



At first sight it is not an easy matter to determine 

 what may be the origin of the highly complicated male 

 and female organs of the plant. Both the sepals and 

 the petals of a flower exhibit more or less resemblance 

 to the foliage of the plant, but there is certainly not 

 much obvious connection between stamens and [)istil 



In the Begonia, the rear relation between stamens and petals is clearly observable. 



compared with the organs which fill up the centre of the 

 typical blossom. These, as is well known, are divided 

 into two distinct kinds — the stamens and the carpels — 

 the latter collectively forming the pistil. The former 

 organs produce the pollen grains which, coming into 

 contact with the latter, fertilise the ovules and thus 

 bring about the production of living seed. As a rule 

 the stamens are in the form of small processes having 

 slender stalks surmounted by heads or anthers; it is on 

 the anthers that pollen is produced. The pistil, as has 

 been stated, is composed of a number of carpels, and 

 these are sometimes verv distinct, or, on the other hand, 



and the leaf. Nevertheless, after the consideration of 

 the instances which it has been the purpose of the pre- 

 sent paper to bring together, it will be easy to credit 

 the statement that the leaf \\as the ancestor of even 

 the reproductive organs themselves. 



In the case of the so-called " double " flowers it will 

 be readily seen that a very large number of extra petals 

 have entered into the composition of the blossom. 

 These additional petals must have had their origin in 

 something, and, as a matter of fact, they are degenerate 

 stamens. The manner in which this transformation of 

 stamens i.-to petals is carried on is readily seen in the 



