MANUAL OF NATURE STUDY. 1^5 
not exactly in the same way. There are many 
of these spores in one single spore-sac and the spore- 
sacs are so numerous and small that you ean scarce¬ 
ly count the number upon a single frond. When 
the sac bursts the air is always dry and considera¬ 
ble breeze stirring. Under such conditions, what is 
done with the spores? These spores, of course, 
take the direction of the wind and are sometimes 
carried great distances, falling upon the ground, 
here and there, all along the way. 
If all ground were good for the growth of ferns, 
the spores from a single plant would soon populate 
the entire globe with ferns; but all ground is not 
good for ferns. These plants are a little particular 
about the sort of ground they grow in. The soil 
must be damp and shady—not too wet, but damp 
or moist. Around old, rotten logs or stumps these 
plants will grow very luxuriantly, if the soil is 
damp and shady. These spores, then, when they 
find lodgment in these damp places, gradually de¬ 
velop into very small discs or flattened leaves which 
spread out upon the damp ground. Each little flat 
leaf, or prothallium , as the botanist calls it, sends into 
the ground many very fine and delicate root-hairs. 
As soon as the prothallium becomes thoroughly fixed 
by its root-hairs, so as to obtain nourishment for 
itself and the young plantlet which it is about to 
give rise to, it develops on the under-surface, 
