224 HOW PLANTS GROW. 



as in some Algce, or branched in a complicated manner, as in 

 Mucor. In the simplest, many-celled plants — such as Fenicillium 

 — we find only a row of cells, one above the other ; next come 

 those consisting of a plate of cells, with many rows side by side, 

 as in some AlgcE. In them, renewal, conjugation, or multiplica- 

 tion, may be the method used. In the higher flowerless plants, 

 and in all the flowering plants, the last only is used. 



It now remains for us to see in what way and by what means 

 the mother-cell of the embryo comes about, and to trace its pro- 

 gress into the adult-plant. This brings us to the second part of 

 our subject : — 



II.— From Cell to Plant. 



Here, in broad terms, I shall describe the processes carried on 

 by the reproductive organs of the plant, in order to show the 

 origin of the primary cell. 



{a) Fertilization. 



The organs of a plant are set in two groups — ist, Those of 

 nutrition, including root, stem, and leaf; 2nd, Those of reproduc- 

 tion, found in the flower. 



A Floiuer consists normally of four sets or circles of organs: — i. 

 The Calyx, usually green, made up of sepals ; 2. The Corolla, 

 inside the calyx, and made up of petals, usually coloured (these 

 two circles are the auxilliary organs of reproduction, subserving 

 only the purposes of protection and attraction) ; 3. The Androe- 

 ciiim, or set of stamens, varying in number and position ; 4. The 

 Gynceciwn, or Pistil, made up of one or more carpels, separate or 

 united (these two circles are the essential reproductive organs, at 

 which we must look for a time^ and ascertain their functions. 



A Stamen consists of a stalk — the filavient, and a club-shaped 



end — the anther. The latter contains in its two lobes certain 



cells, which in turn contain minute grains of powder, often yellow 



in colour, and called pollen-grains. This pollen is the essential 



fertilizing agent, without whose aid no embryo can possibly exist. 



A Carpel consists of a lower part, or body, called the ovary, 

 which is hollow. It ends above in a viscid, cellular tip, devoid of 

 epidermis, called the stig?na, whose cells secrete a sticky fluid ; 

 the stigma may be immediately above the ovary, or raised some 

 distance above it, on a stalk termed the style; this may be absent, 



