217 



native plants, hut wIumi transported to warnior ivirions they blossom 

 and ripen earlier. Thus in 1851) Schueheler sowed (Crowed barley that 

 had been raised in Alten (hit. 70 X.). where it i-ecpiired only nine 

 weeks to ripen, in Christiania (hit. (iO X.), where it ripened in 

 eight weeks. In the same year some of the same bai'ley was carried 

 from Breslau, where it rexpiired nine and a half weeks, to Christiania, 

 where it ripened in twelve to fourteen Aveeks. 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. 



The annual sum totals of heat are 1,300 in Alten and 2,000 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,-1:00° C. required by it at Christiania are not received at Alten. 

 It is onl}^ 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 accust*omed 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 

 doubtle.ss barley from Alten would succeed. Barle}' cultivated in the 

 Caucasus at an elevati(m 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 

 wanner 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 orientalU) re(|uirc 

 more time to ripen than the ordinary oats of northern Europe; the 

 variations in times recpiired by different kinds of oats, barley, and 

 wdieat, 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, Avill disappear after a few 

 generations if the plant has the power of adapting its internal organ- 



