Corn Investigations 
91 
The studies of the comparative effects of foreign pollen 
have by no means been exhaustive, and further investigations 
are suggested. The entire problem is so involved that these 
data are merely offered as a report of progress. 
RELATIVE EFFECTS OF FOREIGN POLLEN UPON EMBRYO AND ENDOSPERM 
WEIGHTS OF INBRED CORN 
The preceding data indicate so clearly an increase in kernel 
weight resulting from fertilization of homozygous (inbred) 
corn with foreign pollen that it becomes a matter of interest to 
know the relative effect upon the various parts of the kernel. 
A grain of corn consists of three main portions, (1) the seed 
coat (x^ericarp), (2) the endosperm or starchy portion, and (3) 
the embryo. The seed coat is a portion of the mother plant and 
can be only indirectly influenced by the character of the pollen. 
The sex>aration of the kernels into their component parts 
was facilitated by soaking them in water for 24 hours. This 
was x^ receded by heating at 100° C. to destroy the viability and 
thereby avoid any growth changes due to supplying moisture. 
After dissection, the resx)ective x^ortions were rendered moisture 
free at 105° C. and weighed. Pure line strains of both Hogue’s 
Yellow Dent and Nebraska TThite Prize rex>orted in Table 34 
were used in these tests. A very brief study was also made 
with ordinary corn of these two varieties for the purpose of 
general conpparison. The results are given in Table 36 and 
summarized in Table 37 and chart 3. 
The manner of obtaining conrparable x^ure and hybrid ker- 
nels has been previously described. As an average for the pure 
lines of both varieties, the immediate effect of foreign pollen 
was to increase the weight of (1) the kernel 11.09 per cent, (2) 
the embryo 20.22 per cent, (3) the endosperm 10.39 per cent, 
and (4) the seed coat 5.36 x^er cent. In contrast, kernels of ordi- 
nary heterozygous corn were not materially influenced in the 
development of their respective parts by fertilization with 
foreign pollen. 
The ratio of embryo to endosperm weight is nearly the 
same for the kernels borne on ordinary heterozygous variety 
plants as for the pure kernels on pure line plants derived by 
inbreeding. This suggests that the embryo and endosperm re- 
duce to about the same degree as a result of continued self- 
fertilization. The proportion of embryo to endosperm is some- 
what greater in cross-pollinated than in pure kernels borne on 
pure line xflants. 
