MANUAL OF NATURE STUDY. 137 



the root point lias developed roots and leaves suflS- 

 cient for an independent existence of the fern 

 plant, the prothallinm withers away just as the 

 seed leaves of a bean do under similar conditions. 

 It will be seen, then, from the foregoing descrip- 

 tion that the fern plant does not reproduce a fern 

 plant immediately, as do beans, peas and other 

 flowering plants ; but that it first produces spores, 

 the spores produce prothallia, and the prothallium 

 in monoecious specimens gives rise to male and 

 female organs, and finally these organs reproduce 

 the fern plant, which again produces spores. Such 

 a process is called alternation of generations. 



Mosses. 



Where do they grow ? On which side of tree do 

 you find them most abundant ?. On which side of 

 rock? On which side of hill? If found on the 

 south side of rock, tree or hill, what must necessar- 

 ily be the other conditions? 



While examining the rocks and trees you will 

 doubtless find a scaly-like plant that spreads out 

 over the rock and sticks very closely to it. This 

 plant is known as one species of lichen. Some 

 people call it moss, but it is not true moss. You 

 will find it quite plentifully distributed over the 

 surface of old marble slabs in grave yards. After 

 many, many years, perhaps centuries, the lichen 



