i879-J 
The Action of Light on Plants. 
789 
approached. Ordinary vegetables and herbs grown in high 
latitudes have a far more aromatic taste than those grown 
in more southern countries. The meadow cumin ( Carum 
Carvi) is an example of this fa£t : grown at Christiana it 
contains 5*8 per cent of volatile oil, whilst that cultivated 
in Germany and Central Russia contains only from 4*0 to 
4*8 per cent. But this large development of aromatic 
essence is not always considered an advantage ; for instance, 
the tobacco plant grown in Norway or other northern coun- 
tries contains, it is said, too much nicotine. In proportion, 
however, as the aroma increases with the latitude the sac- 
charine substances diminish : the berries and fruits of the 
north are less sweet than those which are cultivated or grown 
wild in the more southern parts of those countries. Conse- 
quently whilst Norway as well as Sweden, and even Finland, 
produce the most delicious apples, the pears are not suffi- 
ciently sweet. 
These fadts, as well as the rapid growth of vegetation in 
the northern regions, are attributed to the prolonged adfion 
of solar light. Indeed at Christiana, at the summer solstice, 
the sun remains below the horizon only 5 h. 17 m. ; 
at Froudheim, 3 h. 34 m. At Bodo, the chief town in 
Nordland, the sun does not descend below the hori- 
zon from the 2nd June till the nth July; at Tromso, 
from the 20th May to the 24th July; at Hamerfest, the 
chief town of Finmark, from the 15th May to the 29th 
July. On the other hand, the centre of the sun does not 
appear above the horizon at Bodo from the 14th to the 28th 
December; at Tromso, from the 25th November till the 
16th January; and at Hamerfest, from the 20th November 
to the 2 1st January. 
It is not surprising that barley, potatoes, and many other 
plants and vegetables ripen in the most northern latitudes, 
seeing they are exposed to a considerable amount of heat 
during two or three months of the year. In those regions 
where the sun hardly descends below the horizon in summer, 
there is no night, only a short twilight ; the growing plant 
therefore enjoys permanently, and without interruption, the 
heat and light which it requires. 
