210 LIFE STORIES OF PLANTS 
young embryo fern grows large enough to burst out of 
the prothallium, when the root strikes into the soil and 
the cotyledon or first leaf rises upward, as shown in 
Fig. 255, it is doing precisely 
the same thing that a seed 
does when it germinates, 
strikes root, and lifts its leaves 
and stem upward to the light. 
The generations of the fern. 
The life story of the fern 
reveals to us two generations, 
the prothallium and the fern 
plant. They can live inde- 
pendent of each other. Hach 

one can take water and food 
from the soil. With the leaf- 
Fig. 256. Fern with short, green each one can make its 
thick stem. 
own starch food. The pro- 
thallium starts from the spore on the fern plant, and 
the fern plant starts from the germ in the prothallium. 
The two generations therefore alternate with each 
other, as it were. In the corn, the bean, and other 
plants of this kind there seems to be only one genera- 
tion. This is because one part of it, the prothallium 
generation, 1s packed away and hidden in the embryo 
case as endosperm, while the other part is hidden in 
the pollen and pollen tube. Most plants, then, have 
