412 BOTANICAL GAZETTE [JUNE 
Microchemical study 
UNGERMINATED GRAIN 
Coat.—As the coat of the grain is easily permeable and in no 
way delays germination, no particular study was made of it. In 
general it consists of four layers: (1) the outer portion of the 
pericarp, consisting of one or more layers of cells whose walls 
contain some pectic substance, (2) the inner epidermis of the 
pericarp, in which lignification has occurred, (3) the testa, also 
lignified, and (4) the suberized remnant of the nucellar tissue. 
Glucose is present in the pericarp, undoubtedly a remnant of that 
originally present in the pericarp of the developing fruit (ECKER- 
SON 10). 
ENDOSPERM.—Carbohydraies—Large amounts of starch are 
found in the endosperm, except in the aleurone layer, where it is 
entirely lacking. No reducing sugars are present, but a small 
amount of sucrose can be identified. 
Fats.—Most of the cells of the endosperm contain very little 
fat, but it is abundant in the aleurone cells. 
Proteins.—Proteins also are found in the starch-containing cells 
of the endosperm, and these are known to be almost entirely the 
storage proteins, glutenin and gliadin (OsBorNE 16). These can- 
- not be distinguished from each other by microchemical methods. 
In the aleurone cells storage proteins are absent, but other protein 
material is present in considerable quantity. 
Oxidizing enzymes.—No oxidase is found, but both peroxidase 
and catalase are present. 
Minerals.—Little potassium is present, but considerable calcium 
and magnesium. Small amounts of phosphates were detected, 
while the aleurone layer has much iron. As noted under the 
embryo, no sulphur could be identified. 
EmsBryo.—Carbohydrates.—Sucrose is the only storage carbo- 
-hydrate found in the embryo of the Marquis wheat. In some 
forms, such as Emmer, starch is found in the scutellum. 
Fats.—Fats are found in all parts of the embryo. 
Protein,—The embryo gives a strong protein reaction, although 
probably no storage proteins are present. No amino acids can be 
detected by microchemical methods. 
