as 
217 
native plants, but when transported to warmer regions they blossom 
and ripenearler. Thus in 1859 Schuebeler sowed 6-rowed barley that 
had been raised in Alten (lat. 70° N.), where it required only nine 
weeks to rigen, in Christiania (lat. 60° N.), where it ripened in 
eight weeks. In the same year some of the same barley was carried 
from Breslau, where it required nine and a half weeks, to Christiania, 
where it ripened in twelve to fourteen weeks. Linsser arranged these 
experiences as shown in the following table, in which he assumes that 
both at Alten and at Christiania the barley is sown when the mean 
daily temperature is about 8° C. 
hee 
Janine Date of | Date of : Sums of 
Barley raised at— sowing. |ripening. Interval. Penapere 
Weeks. Con 
Alten and sown at Alten -_-....--....--- pee eae eae c June 14 | Aug. 16 9 | 700 
Altenandisown at Christiania! --_.-..:-2.22.<-..--2_------- | May 5| June 29 ei ieee BAU 
Christianaand sownat Christianae--- = -so52)22 282 ee do ....| Aug. 1-9 13 | 1,400 
The annual sum totals of heat are 1,300 in Alten and 2,600 in Chris- 
tiania. Therefore we see that the heat required by seed acclimatized at 
Alten (700) is to that required by seed acclimatized at Christiania 
(1,400) in the same ratio as the annual sum totals. 
It can also be shown that barley acclimatized at Christiania and 
transported directly to Alten can not ripen in the latter place, since 
the 1,400° C. required by it at Christiania are not received at Alten. 
It is only by gradual progressive acclimatization at numerous inter- 
mediate places that the plant has been enabled to adapt itself to suc- 
cessively smaller sum totals of heat. In continuation of this process 
the barley that is now accustomed to ripen at Alten can be used to 
pioneer the further northward progress of its species. The attempt 
to transport barley from Denmark to Iceland has thus far failed, but 
doubtless barley from Alten would succeed. Barley cultivated in the 
Caucasus at an elevation of 7,000 feet and transported to St. Peters- 
burg should, according to Linsser’s computation, experience an accel- 
eration, so far as climate is concerned, as though it were coming to a 
warmer climate, but this acceleration may be more than counter- 
balanced by the differences in the nature of the two species of plants, 
as it is well known that the Turkish oats (Avena orientalis) require 
more time to ripen than the ordinary oats of northern Europe; the 
variations In times required by different kinds of oats, barley, and 
wheat, and even winter rye, are oftentimes larger than the variations 
due to differences of climate. But such variations, as observed in 
plants that are only partially acclimatized, will disappear after a few 
generations if the plant has the power of adapting its internal organ- 
