1921] CHOATE—WHEAT GERMINATION 4II 
begins toward the outside of the endosperm, the resulting sub- 
stances diffusing out and away from the embryo, while in the dark 
it begins near the embryo, which can then make use of the hydro- 
lytic products. The presence of iron in the seed coat, acting 
catalytically in the light, is undoubtedly a factor in the first 
case. 
With the development of microchemical technique a method 
has become available by which qualitative determinations can be 
made for the presence or absence of many substances’ without an 
undue expenditure of time, and in this way, especially when : 
checked with macrochemical analyses at crucial points, the time 
and place of chemical changes can be determined with greater 
accuracy than heretofore, as the following results show. 
Method 
The material used in this study was Marquis wheat, a hard 
spring wheat, procured from the Albert Dickinson Company of 
Chicago in the fall of 1917 and again in ro19. In most cases the 
ungerminated grains were soaked for two hours in distilled water 
in order to facilitate sectioning. No differences could be observed 
in the chemical condition of grains thus soaked as compared wi 
unsoaked ones. For germinated material the grains were soaked 
for two hours and then placed in covered Petri dishes with moist ° 
filter paper on the bottom. These dishes were placed in a dark: 
room kept at 16°-20° C., unless otherwise noted. When the period 
of germination covered several days the dishes were opened daily 
and the air renewed. Sections were cut freehand, and the micro- 
chemical tests employed were those recommended in the standard 
works by Mo.iscu, TUNNMANN, and Cuamor. A list of the tests 
used will be found at the end of this paper. Methods used in 
determinations other than microchemical ones are described in 
appropriate places. The germination period was regarded as 
seven days, in part because of the difficulty of growing seedlings 
longer under the given conditions, but mainly because by the end 
of that time the seedlings had so far developed that, had they been 
growing under field conditions, they would have been making their 
own food, without dependence upon the endosperm. 
