LIFE HISTORY OF THE MALE FERN 65 
tion. According to the theory of Willstatter which is not as yet 
generally accepted, COs is first united with chlorophyll to form a 
compound, the atoms of this compound become rearranged to 
form a peroxide which later is decomposed by catalytic enzymes 
with the liberation of free oxygen. The formation of starch may 
be expressed by the following equation: 6CO, + 5H:O = 
CsHi005 + 602. The molecules of glucose and starch contain 
stored-up energy. A portion of the grape sugar is removed from 
solution by the chloroplast and converted into starch which is 
stored up within it; another portion is used to nourish the proto- 
plasm of the cell. But the greater portion of sugar manufactured 
descends in solution through the phloem cells of the bundles of 
the veins, mid-rib and stipe to the stem or roots, where it is 
removed from solution by the action of the leucoplasts which 
convert it into reserve starch. 
Sugar and starch, however, are not the only food materials 
manufactured in the leaf. Proteins are likewise formed. These 
are composed of carbon, hydrogen, oxygen, nitrogen, sulfur and 
sometines phosphorus. They are formed from grape sugar 
with the addition of nitrogen and the other elements by the living 
protoplasm. The source of nitrogen, sulfur and phosphorus is 
the mineral salts which are found in the crude sap. These 
proteins descend through the sieve tubes of the veins, midrib and 
petiole to the stem and roots, nourishing all of these parts with 
protein material. The surplus protein material is stored in 
various cells for future use. 
Not all of the water carried to the green cells of the leaves by 
the tracheids is used in the manufacture of sugar and starch. 
Some of it is employed in chemical reactions taking place within 
the cells and, some by the protoplasm itself of these cells for the 
purpose of repair. Whenever there is a surplus of water in the 
cells of the leaf, some of it escapes into the intercellular-air- 
spaces as water-vapor. When the humidity of the external 
atmosphere is less than that of the air-spaces, the water vapor 
passes out through the stomata. The passage of water vapor 
_ through the stomata is called TRANSPIRATION. 
All of the living cells of root, stem, leaf as well as other organs 
of the fern require oxygen. This gas enters the plant through the 
