NATURE OF PLANTS 



III 



structures. The important part of the sporophyll is the spore. 

 A spore is a cell that is capable of germinating or growing under 

 favorable conditions and thus producing some kind of a new 

 organism, or we may say a new plant. You are always to think 

 of a spore as having this power. In case of the spores under 

 consideration very rudimentary plants are produced that con- 

 sist of only a few cells. These minute plants are very important, 



Fig. 76. 



Fig. 77. 



Fig. 76. Section of the ovule of the Canada lily (greatly magnified): 

 mi, micropyle; i, integuments; n, nucellus, here consisting of a single layer 

 of cells, but it often forms a large mass of cells; mg, megaspore with large 

 nucleus in center. This spore is about to divide; /, stalk or funiculus which 

 attaches the ovule to the wall of the ovary. 



Fig. 77. Germination of the megaspore: A, first division of the nucleus 

 of the megaspore. B, second stage in the germination, four nuclei being 

 formed. C, Unal stage in the division of the nuclei. 



however, because they contain the male and female cells, or 

 gametes, so called because they unite, thus forming a new spore, 

 the gametospore, quite different from the micro- and mega- 

 spores. So let us not lose sight of the fact that these apparently 

 insignificant micro- and mega-spores germinate and produce 

 minute plants that are quite distinct from the plants that bore 

 them. We shall first follow the germination of the megaspore 



