true. In some cases spores may be merely cells formed 

 by pinching off pieces, so to speak, at the ends of thread- 

 like branches. In these cases they might be thought of 

 as a kind of bud. This is the case in the spores of toad- 

 stools and their close relatives. 



The spores of plants are varied in such a way that 

 they meet the needs of the plants in remarkable fashion. 

 They may be formed deep inside certain organs and so 

 need special devices to let them out, such as the active 

 bursting of a capsule; or they may be formed in the air 

 at the very tips of delicate branches, so that the least 

 disturbance breaks them off and sets them free. The 

 spores of the various molds and fungi that live in the air 

 and on solids are without any power of self motion. On 

 the other hand, most of the spores of the lower algae, 

 which live in water, have cilia and can make very definite 

 and interesting motions through the water. 



In some plants only one spore may be formed at a 

 place; in others they may run into the thousands. Spores 

 even in the same plant may differ much in size, depending 

 on the way they are formed and the period of 

 development to which they belong. 



5. Kinds of Plants That Bear Spores. For a long time 

 the plant kingdom was divided into those plants that 

 reproduce by means of spores, and those that reproduce 

 by means of seeds. Among the so-called spore-bearing 

 plants we included the algae, the fungi, the liverworts, 

 the mosses, the ferns and their kindred. We now know 

 that the higher plants, that is, those with flowers, also 

 bear spores, and that the flower itself is a spore-producing 

 organ, as well as a seed-producing organ. This will be 

 discussed at more length later. 



6. How Spones Behave. They are reproductive bodies 

 looking wholly to the next generation. As compared with 

 other cells in the mother plant the spores are usually 

 highly resistant. Often they float around in the dry air 

 without hurt. Many of them will stand cold much below 

 the freezing point of water. In many of the parent plants 

 these conditions would mean death. On the other hand, 

 the swimming spores are usually remarkably delicate and 

 easily destroyed. 



While the spore usually does not have the power of 

 growing in the ordinary way, nor of dividing into two 

 spores as the bacteria divide, it has a definite manner of 

 returning to life and activity. Usually the cell wall around 

 it is a little tough. When conditions are favorable, as for 

 example, after one of these spores has been floating 

 aiound in the atmosphere and comes into a moist place 

 where its food is abundant, it takes up water and begins 

 to swell. It then sends out through the softened or 

 broken wall a delicate tube of its protoplasm, surrounded 

 by a thin membrane. This tube is the beginning of a 

 new plant. This process by which the spore starts the 

 new plant is called germination. 



Germination differs very much as to time. In some 

 kinds of spores germination may begin within a few hours 

 after the spore escapes. This is true of the ordinary 

 spores of the bread molds. One may readily see these 

 spores germinate, and begin to form the fine threads of 

 the mold, by placing on an ordinary glass slide a decoction 

 of bread or fruit juice and dusting it with spores. If this 

 is placed in a moist chamber and watched at frequent 

 intervals during twenty-four or forty-eight hours, the 

 observer will see stages of germination. If conditions 

 are not favorable, the spore may withhold germination 

 for considerable time without hurt. Some other spores 

 will not germinate even under the most favorable 

 conditions until after a period of rest. 



Among the fresh water algae, many of which flourish 

 in ponds that are liable to be dried up in late summer and 



frozen up in the winter, resting spores often enable the 

 species to survive these conditions. Drouth would kill 

 the parent plants or the more delicate kinds of spores. 

 Freezing would be likely to do the same. The restmg 

 spores, often with thick walls, are unhurt. Furthermore, 

 even though the moisture and temperature are right, the 

 food required by the organism may not be present. In 

 such a case germination would be disastrous, because the 

 young germinating plant is very tender. 



We see then that spores reproduce the plant, but they 

 do more than this. Because of their variety in form and 

 in behavior they serve to help adjust the species to some 

 of the unfavorable features in its surroundings and to 

 help it take advantage of the favorable ones. 



CHAPTER SIX. 

 SCATTERING THE SPORES 



1. The Problem of Scattering Offspring. Human 

 parents have a way of wanting to keep their children at 

 home and to have them settle near by. But if there are 

 ten children in the family and there are only two hundred 

 acres of land, it is clear that each child must be content 

 with twenty acres or must crowd out some neighbor. 

 Now the problem of these plants that produce so many 

 spores is even more difficult. If all the spores produced 

 by one fungus of almost any kind were to fall right 

 down and germinate on the spot, the crowding would be 

 such that none could thrive. Furthermore, the food at 

 one spot suitable for a given species is always limited. 

 By the time the spores appear the parent plant may have 

 itself exhausted the food. Evidently the species will have 

 a much better chance to keep going if these spores are 

 scattered far and wide. It is sure that most of them will 

 fall at points where they can never succeed, but out of 

 the many there is a chance that some will find favorable 

 places. Wide scattering gives an opportunity to try out 

 the surroundmgs. Since a single spore cannot try first 

 one locality and then another, as an animal can, this 

 scattering of the offspring is the next best way of getting 

 the members of a species at favorable places. 



2. Another Problem. There is another side to this 

 question of scattering. If, for example, there is an injured 

 fish in the water of a pond, and a few spores of the fish 

 mold should light upon it and germinate and get a footing, 

 we have two distinct problems. One of them, the 

 scattering of the young of the species far and wide, was 

 mentioned in the preceding section. The other grows 

 out of the fact that this fish, before it has completely 

 decayed, can support many plants of the fish mold. 

 Therefore it is a clear gain to the species if this mold 

 has a way whereby it can quickly take possession of the 

 fish. The same problem we find in the molds on a culture 

 made of a slice of bread in the laboratory. Both of these 

 classes of organisms have devices for taking full 

 possession of a limited area quickly, as well as devices 

 to extend the species to other spots. In the fish mold, 

 aside from the branching threads of the original parents 

 which spread rapidly over the fish, there are small, short- 

 lived swimming spores that germinate quickly and start 

 new plants near at hand. They are free swimming and 

 might move to considerable distances in the water, but 



