DISCOVEEY OF MAEQTJIS WHEAT 221 



mass, the other twenty-fifth part being occupied by the 

 embryo. The floury part of a grain in which the starch 

 and proteins are stored is known technically as the endo- 

 sperm and consists of about a quarter of a million cells. 

 To protect the embryo and the food-laden endosperm of 

 the kernel under discussion, two coats were developed, one 

 from the skin of the ovule and the other from the wall of 

 the ovarial chamber. The former, known as the testa or 

 seed-coat, soon came to press tightly against the latter, 

 known as the pericarp, so that in the end, a single com- 

 pound horny layer came into existence on the exterior of 

 the grain. Since this layer was red, the grain, when 

 viewed from without, was found to possess the red color 

 which is so much preferred to white for the hard wheats 

 of Canada. 



When the cross-bred kernel was planted in the spring, 

 the embryonic plant within rapidly increased in size and 

 soon pushed several roots dovrai into the soil. It then 

 forced its shoot upwards into the sunlight where it ex- 

 panded its first green leaf. Thus the embryo grew into 

 a seedling. All this early development was accomplished 

 at the expense of the starch and proteins, the reserve food 

 materials which had been stored up in the endosperm or 

 floury part of the kernel in the preceding summer. These 

 substances, when germination began, became converted 

 into soluble compounds, the starch breaking up into sugar 

 and the proteins into simpler nitrogenous bodies. The 

 sugar and nitrogenous bodies, after becoming dissolved in 

 water, were then gradually absorbed by the enlarging em- 

 bryo, the organ of absorption or cotyledon being a shield- 

 shaped structure attached to the axis of the embryo at the 

 place of union of the shoot and the first root. In the 

 course of about 115 days, the embryo grew into a seedling 

 and the seedling into a mature plant. The green leaves 



