M. Berghaus on the Epochs of Vegetation. 183 



occurs in one and the same season in different years exercises 

 a great influence on the epochs of germination. In fact, we 

 not unfrequently see that seeds of the same plants gemmate 

 much earlier when the spring arrives soon, and a mild rainy 

 winter had preceded it, hut much later when the heat of 

 spring has heen delayed hy a severe winter. 



Fronde, cence, that is the unfolding of the leaf-buds is sub- 

 jected to the same changes which are observable in the ger- 

 mination of seeds ; for the difference of climate and that of 

 the seasons exercise the greatest influence on this second epoch 

 of vegetation. 



The Lilac (Syringa vulgaris) unfolds its leaves, 



In the neighbourhood of Naples (Lat. 41°), in the first half 

 of the month of January. 



Near Paris (Lat. 49°), as observed during many years, on 

 the 12th March, as a mean. 



In the middle districts of Sweden, Upsala (Lat. 60 ), at the 



beginning of March. 



The Elm (Ulmus campestris) unfolds its leaves, 

 At Naples, at the beginning of February ; 

 At Paris, in the month of March ; 

 In England, on the 15th April ; 

 At Upsala, in the middle of March. 

 The Birch (Betula alba) unfolds its leaves, 

 At Naples, in the month of March ; 

 At Paris, in April ; 

 In England, the 29th March ; 

 At Upsala, in the first days of May. 

 The Beech (Fagus sylvatica) unfolds its leaves, 

 At Naples, towards the end of March ; 

 In England, the 1st May ; 

 At Upsala, in the first days of May. 

 The Lime-tree (Tilia) unfolds its leaf-buds, 

 At Naples, towards the end of March ; 

 In England, the 13th April ; 

 At Upsala, in the first days of May. 

 The Oak (Quercus) unfolds its leaves, 

 At Naples, the beginning of April ; 



