May 3, 1924 Relative Merits of Sweet Com Varieties for Canning 435 
but the difference in sweetness was much less marked than the figures would 
indicate. In the Boone County White at the 15-day stage the percentage of 
sugar was found to be about equal to any of the sweet varieties at this stage, but 
it was distinctly less sweet to the taste, due, apparently, to its higher moisture 
content, and hence a greater dilution of the sugar and to its smaller proportion 
of cane sugar. Where moisture content and other constituents are about equal, 
differences in sweetness are more nearly proportional to the differences in the 
percentages of sugar. In such cases the higher the percentage of sugar the 
higher the quality of the product. 
There are, probably, other factors which affect the relation of sweetness to the 
percentage of sugar as practically all the 30-day samples of canned corn appeared 
less sweet to the taste than would have been indicated by the sugar content. 
THE THUMBNAIL TEST 
Judging of the chemical composition of corn in the field by the appearance of 
the ear or by the application of the common thumbnail test leaves much to be 
desired. When the test is applied to a number of varieties of the early, medium 
and late sorts it is not dependable and may be entirely misleading. It may be 
and is applied with considerable accuracy in judging of the maturity of a single 
strain with which the person making the test is familiar, but so great have been 
found the differences in composition of different varieties giving comparable 
results with the thumbnail test that except for indicating what would be the 
consistency of the canned product from the sweet varieties it proved of but little 
value. For instance, Crosby corn at the 20-day stage by the thumbnail test 
would have been judged to be at about the same stage of maturity as Stowell’s 
Evergreen at the 25-day stage, but the chemical analyses showed that they were 
far from having the same composition particularly with respect to sweetness. 
When used upon field varieties the test was found still more unreliable as it 
did not prove a safe index even of what the consistency of the canned product 
would be. Boone County White field corn at the 30-day stage would have been 
judged by this test to be only slightly more mature than Crosby at 20 days, 
and yet the consistency and texture of the products from the two varieties at 
these stages were as unlike as could be imagined; the Crosby being excellent in 
body and texture and the Boone County White so solid and tough that it could 
be removed from the can with a spoon only with great difficulty. 
Failure of workers to take these facts into consideration has made the proper 
interpretation of their results extremely difficult if not impossible. Canning 
maturity is more closety associated with the age of the ear than with the physical 
condition of the kernel contents. Therefore, it is particularly important in 
experimental work that the investigator know as closely as possible the exact 
age of his material. 
IMPROVEMENT OF VARIETIES 
One of the chief values of a study of this sort is the help it affords by indicating 
the line of procedure which should be followed in the improvement of varieties of 
corn used for canning purposes. 
In view of the importance of the tenderness of the kernel to the quality of the 
canned product it is believed that no greater service could be rendered by sweet- 
corn breeders than by giving attention to the development of tender strains from 
the standard canning varieties. 
From the figures upon percentage yields of cut corn it is of interest to note 
that for both the yellow and the white varieties the highest yields were produced 
in this instance by the close-grained or many-rowed corns having deep kernels' 
and correspondingly small cobs. The closer the kernels are set in the ear the 
96035—24t-3 
