DISTINCTIONS IN CULTIVATED BARLEYS. 
21 
merits at St. Paul and at Aberdeen were made by the writer, while 
those at Chico were made by Mr. E. L. Adams. The result is shown 
in figure 16. As a whole the variations were parallel, Xos. 6 and 35 
being strikingly so. The four less dense selections showed an extreme 
variation of only three units, while the two dense selections varied 
much more. In Xo. 32 this was due in part to poorly developed 
heads; at St. Paul, particularly, its spikes were so short that it was 
impossible to find many in which five successive nodes bore fertile 
florets. The effect of sterility is to lengthen the internode of the 
rachis. All types were most dense at Chico and least dense at St. 
Paul. The effect of irrigation as shown 
at Aberdeen was very slight, especially 
when compared with the effect of the 
combined factors of geographical loca- 
tion. 
The character of the curves was in- 
fluenced even less than their relative 
density. Table V shows the distribu- 
tion into their various densities of 100 
spikes from each of 59 plats of barley. 
By referring to Table V it will be seen 
that some selections always present a much 
sharper curve than others, and thus af- 
ford opportunity for varietal distinc- 
tions in the distribution of the measure- 
ments. Avoiding the extreme examples, 
it will be noted that the spike of No. 30, 
for instance, which has already been 
condensed three or four units by the use 
of the formula for density, is still less 
compact than Xo. 35. which by the same operation has been made 
to appear slightly less compact than it really is. At St. Paul, Xo. 35 
has a total of 85 per cent of its spikes within three units in one in- 
stance and 91 per cent in another, while Xo. 30 has but 82 per cent 
within this limit. At Aberdeen, imder irrigation, Xo. 35 has a total 
of 91 per cent of its spikes within three units, while Xo. 30 has but 
78 per cent ; upon the dry farm at the same place, Xo. 35 has a total 
of 81 per cent of its spikes within three imits. while Xo. 30 has but 
77 per cent ; and at Chico, Xo. 35 has 91 per cent of its spikes within 
three units, while Xo. 30 has 91 per cent. 
<l 
40 
39 
33 
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36 
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S A 
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at 
V 
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26 
25 
24 
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Fig. 16. — Curves showing the 
average density of six selections 
of barley grown at Chico, Cal., 
at St. Paul, Minn., and on irri- 
gated and unirrigated land at 
Aberdeen. Idaho. 
