12-4 



climates because of a short vegetative period, is lost after four or five years 

 of cultivation in lower latitudes. Conversely, long-lived varieties accustom 

 themselves in a few years to a short vegetative period. Yellow chicken 

 maize from Hohenheim, for example, which ripened in 1852 at Christiana 

 in 120 days after repeated sowings, shortened its growth period to the extent 

 of 30 days in 1857. In Christiana the developmental period of barley is 90 

 days, but seed brought from Alten (the 70th parallel) needed only 55 days 

 (see Kowalewski). 



Of the chemical properties developed in a nortliern habitat, which in 

 great measure correspond to the changes in plants in high elevations, the 

 fact that the sugar content of the fruits decreases toward the north while 

 the aroma increases is of especial importance. Bonnier and Flahault main- 

 tain also that not only the size of the leaves increases in the darkness of the 

 north but also their green color^. Schiibeler's experiments in summary- 

 give the following special examples : — In wheat brought from Ohio and 

 Bessarabia, the grain became darker in color each year until it was as yellow 

 brown as the native Norwegian winter wheat. vSimilar results were obtained 

 with maize, beans, peas, celery, etc. Celery taken from a region extending from 

 the Caucasus to Hindustan, grows in Africa (Egypt, Abyssinia and Algeria) 

 and may be found in Europe from the Mediterranean to the Baltic ; it now 

 extends even into Finland up to the 69th parallel. There, however, the root 

 stalks are poorly developed ; — the aroma, nevertheless, becoming more 

 pungent^. The greater intensity of color in the blossoms, as already men- 

 tioned, a peculiarity shown to correspond with an increasing elevation above 

 sea-level, also appears in most garden flowers as cultivation advances to- 

 wards the north. In regard to the formation of aromatic substances, be- 

 sides celery, juniper may also be cited as an example. In Norway it is much 

 richer in oil than in Central Europe. Onions also and garlic are uncom- 

 monly pungent in Norway. Strawberries are sour but aromatic, while, 

 according to Gotze, they are exceedingly sweet in Coimora, but almost with- 

 out any aroma. Plums often remain so sour that, compared with fruit 

 brought from more southerly regions, they still seem immature. A similar 

 condition exists with grapes as shown by comparing the sweet Portugese 

 grape with the less sweet but aromatic Rhenish grape. 



In considering the horizontal differences, expressed in the decrease of 

 rainfall and increase of clearness of the air, from the west towards the east, 

 in the conditions of light between southern and northern regions etc., we 

 should not forget one circumstance, to which de Candolle* has already 

 called attention. This, to be sure, has not been sufficiently verified experi- 



1 Bonnier et Flahault, Observations sur les modifications des vegetaux suivant 

 les conditions physiques du milieu. Annal. d. sc. nat. Botanique, t. VII, Paris 1879, 

 p. 93. 



2 The effects of Uninterrupted Sunlight on Plants. Gard. Chron. 1880, I. p. 272. 



3 Hansen, C, Der Sellerie. Gartenflora, 1902, p. 18. 



4 de CandoUe, A., Sur la methode des sommes de temperature appliquee aux 

 ph€nom&nes de la v4g6tation. Archiv. des sc. physiques, etc. Nouv. ser. LIU. L.IV. 

 Genf 1875, cit. Bot. Jahresber. 1875, p. 585. 



