2S On the Heat of Springs, [July, 



The northern plants, which cease to vegetate at Upsala, or are 

 very seldom seen there, but which are very common at the lake 

 Yngen, and which reach their southernmost limit at Upsala, are 

 the following: — 



There covers the zone. Temperature of the earth. 



Bubus chameemorus From 43'?° to 3v8° 



Linncea bore lis From 44*06 to 35 *6 



Polygonum viviparum From 44*06 to 3.5 - S 



Cafla palusirii (a smaller zone) From 44 "42 to 37*4 

 Trientalls Europcea From 44*06 to 34*7 



Andromeda polijolia, scheuchzeria, car ex leucoglochin. 



The Lake Yngen. 



The southern plants which reach their northern limit at the lake 

 Yngen, which ire seen there hut seldom, though ihey ate common 

 about Upsala, are the following: — 



The mil [fraxinus excelsior), and the common guelder rose {vibur- 

 vum opnlu ), do not grow here in exposed situations, but require 

 the peculiar shelter of very narrow valleys. The maple (acer plata- 

 movtes), and the lime-tree, are to be found only on some peculiar 

 acclivities .vhich are very favourably exposed to the powerful action 

 of the sun's rays. There likewise, and only there, are to be seen 

 two miserable hazle bushes. Saxijraga gran/data, hyoscyamus, 

 and leommis cardiaca, reach cjuite as far as Storjbrsbruck. There 

 occur likewise, rosavillosa, salix fusca, galium veritm (verbafcum 

 thapsus, geranium sanguineum, and orobns vermis, only in one 

 place, by Pehrsberg; phellandrium aquaticum, only in Nykytta- 

 elj,) antirrhinum linaria, geranium robertianum, linum catharcti- 

 cum, ophrys ovata, &c. Alnus glutinosa is likewise found in 

 abundance. It disappears when the temperature of the earth sinks 

 to 59*2°. Attempts have been made to cultivate the horse-chesnut 

 {cpscuhts hippocastanum) near Gammalkrappa ; but as the branches 

 are annually frozen, the stem always at last dies before it has 

 reached the height of a fathom. Equally unsuccessful have the 

 attempts been to raise fruit-trees in this place. 



The northern plants which reach their southern limit at the lake 

 Yngen, and are only first seen considerably to the north of Upsala, 

 are — 



Temperature of the eartk 

 necessary for their growth. 



Alnus incana From 41° to 36-5° 



Betula nana From 4 1 to 33*8 



Car ex glolularis, a peculiar small zone . . . .From 41 to 37"4 



Carex limosa, irrigua, livida, and scirpus ccEspiloms. 



We might easily believe that plants penetrate by their roots to so 

 small a depth in the ground as to be able to experience, in a greater 



