1 86 THE SWAN AND HER CREW. 



Now it is peculiar to ferns, that the cases in which these 

 spores are enclosed grow directly from the veins of what is 

 usually called the leaf, but is more correctly termed the frond, 

 and always appear upon the back or at the margin. 



Ferns, then, are flowerless plants which bear their spores in 

 cases growing upon the back or margin of the leaves. 



In order that the phenomena of growth and fertilization in 

 ferns may be clearly understood, it is necessary to refer to the 

 process as taking place in flowering plants. The tulip is most 

 appropriate for an illustration, inasmuch as its various parts will 

 be recognised with ease. 



At the bottom of the blossom is a thick green oval body 

 called the ovary, which afterwards becomes the seed-vessel. 

 At the top, this narrows into a short column, surmounted by a 

 three-cleft knob. Between the ovary and the gorgeously 

 painted flower-leaves are six curious organs, termed stamens, 

 consisting each of a long and rather slender stalk, and a head 

 formed somewhat like a hammer. 



If the green oval ovary in the centre is cut in two, it will be 

 found divided into three chambers, in one or another of which, 

 not usually in all, will be seen a row of little knobs or buttons 

 attached to the partition in the middle. These little buttons 

 are ovules, or seed-germs, and the special office of the ovary is 

 to produce these germs, and to contain them until their full 

 development and complete ripening into seeds. But if the 

 knobs are left just as they are, unfertilized, they can never 

 become seeds, and the plant will fail to reproduce its kind. 



Turn we now to the stamens. Each of their hammer-like 

 heads has two chambers, full of beautiful little grains which are 

 called the pollen. Each grain is tastefully and delicately 

 marked, and holds a transparent watery fluid, in which 

 a number of extremely small solid particles are floating. 

 What is required for the fertilization of the seed-germs isthat 

 this fluid should be conveyed to and taken up by them. But 

 they are in the centre of the thick green ovary this in the 

 chambers of the stamens ! 



A simple arrangement brings all about. At a certain time 

 we may see the black heads of the stamens covered with a fine 

 flour, which adheres to whatever touches them. This flour is 

 made up solely of pollen-grains, escaping in unimaginable 

 numbers from the chambers where they are produced. At the 



