May 3 ,1924 Relative Merits of Sweet Corn Varieties for Canning 417 
These results are typical of those obtained with all varieties, though in some 
instances greater differences in the range of toughness of individual kernels 
were observed, as well as, occasionally, greater differences in the averages for 
the test ears. On the whole, the results of these tests showed clear-cut and 
significant differences in the toughness of the kernels at different stages of 
maturity, as will be shown by the curves which follow shortly. 
What was at first a surprising result in the test upon individual ears was the 
finding that the kernels at the butt of the ear as well as at the tip were distinctly 
more tender than those nearer the middle. This was found to be almost uni¬ 
versally true, and in searching for the explanation it was thought that these 
differences were probably due to differences in age of the kernels as determined 
by the time of pollination of the silks. This idea was confirmed in conversation 
with Dr. C. P. Hartley, of the Office of Cereal Investigations, who has demon¬ 
strated that the silks from the middle portion of the ear are the first to appear 
and hence are first to become pollinated. 
With the increase in maturity there was found to be a progressive increase in 
the resistance of the kernels to puncture. This will be shown by the series of 
curves of the different varieties of sweet corn tested which are presented here¬ 
with. As is to be expected of curves based upon the findings from but relatively 
few ears, irregularities in form are observed. These of course would be absent 
in curves based upon a larger number of tests. 
Little comment upon these curves is necessary. Their outstanding feature 
is the pronounced and rather rapid rise indicating increasing toughness of the 
kernels. In no case did corn remain tender for any considerable period, though 
a tendency in this direction is shown in the case of Golden Bantam. Some 
varieties are distinctly tougher than others even while immature, as is shown, for 
instance, in the case of Crosby. (See fig. 4.) This slightly greater toughness 
of the Crosby, in some strains at least, was also observed in field studies in Maine 
during the 1922 canning season in which ears of about the same degree of maturity, 
as indicated by the thumb-nail test for the condition of starch, gave a little higher 
reading than was considered normal for most varieties at that stage grown at 
Arlington farm. Extreme toughness was attained by Country Gentleman (see 
fig. 6) and Kelly's Hybrid (see fig. 5) during the later stages, while several others, 
as, for instance, Golden Bantam, Dreer's Golden Giant, and Charlevoix (see fig. 4), 
did not approach an extremely high mark even at the end of 30 days. While 
these findings can not be analyzed in too great detail, being based upon the results 
of one season's work only and in a restricted area, they do show significant 
tendencies which deserve more careful study. It may be of interest to note the 
relation of toughness as indicated by these tests to corns in prime condition for 
canning. Conclusions drawn from these laboratory tests were surprisingly closely 
confirmed by a number of trained canning factory superintendents who were 
asked, during visits to various plants in Maine, to select ears from cannery stock 
representing corn in prime canning condition, ears that were immature, and those 
that were over mature. These combined to place the critical period, when corn 
was in prime condition, at the stage in which readings from 250 to 300 grams 
were obtained by use of the puncturing instrument. The reading of 325 grams 
was found very close to the “danger line" except in the case of some strains of 
Crosby mentioned above, which often were found to be still in the milk stage 
when this reading was obtained. Tentative conclusions based upon laboratory 
tests at Arlington experiment farm, Virginia, had already placed the readings 
of 250 and 325 as limits to the period during which the different varieties were in 
best canning condition. 
It has not been possible in the present work to study fully the relation of tem¬ 
perature and other climatic factors to the increase in toughness of corn during 
