294 



ELEMENTARY BIOLOGY 



All fungi, mosses, and ferns, and even the flowering plants, 

 produce spores in very large quantities (see Fig. 125). 



The mosses produce spores in rather larger capsules on the 

 ends of very delicate but stiff stalks growing out of the top of 



FIG. 127. Spores of fern 



a, back of a fern leaflet, showing arrangement of sort (singular, sorus), or clusters of 

 spore cases ; &, section through a sorus, showing spore cases with inclosing layer of 

 thin tissue ; c, single spore case, greatly enlarged ; d, same bursting open and dis- 

 charging spores by the sudden straightening out of a row of thick-walled cells ; e, spores, 

 greatly enlarged ; /, spore germinating into a new plant 



the leafy stem. Ferns produce spores in little capsules found 

 in groups on the undersurface of the leaves, or, in some species, 

 right under the edge (Figs. 126 and 127). 



341. Spores in animals. A number of one-celled animals 

 related to the ameba produce spores in a manner that can be 

 compared to the process described in the yeast plant. But the 

 number of spores produced is usually very large, and in some 

 cases the spores do not have thick walls, but are rather active. 

 The protozoon that is the cause of malaria is related to the 

 ameba, and is parasitic on the red blood corpuscles. When 

 the mass of protoplasm has grown to its limit, it breaks up 

 into a large number of pieces, and these are thrown into the 



