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mammals etc.; but as only very few seeds of the digested or undigested 

 fruits are able to germinate, the plant for the most part spreads vege- 

 tatively. The germination takes place in September, but a longer primary 

 shoot is not developed until the next year. Fig. 1 is a drawing of a one year 

 old seedling. In 1918 only cot and B are developed; in (April) 1919 the 

 length increment only reached to Gr; the remainder of the shoot is devel- 

 oped in June. In the following years the primary shoot begins to branch 

 (k) from the base. 



The winter buds are protected by bud-scales as shown in Fig. 4. 

 The position of the bud scales is shown in the diagrams in Fig. 9 ; they 

 are persistent on the plant as long as the green leaves (1—3 years). 



On the primary shoot the leaves are always opposite, but on the lateral 

 shoot we early find a position in a spiral with 2 / 5 divergence; the next posi- 

 tion is a whorl with 3 leaves, the next a 2 / 7 spiral. If we indicate a whorl 

 of 3 leaves by 2 / 6 , a whorl of 4 leaves by 2 / 8 an( i so on > the evolution of the 

 positions of the leaves might be indicated as follows: 



2 m ^ 2 m v ? m v 2 m V 2 m v 2 m v 2 m v 2 m v 2 



A shoot developed in one year has often 2— 3 of these positions: one 

 at the base another at the apex; when two such positions are spirals, 

 these are antidromous. If the first 2 / 5 -spiral on a shoot turns to the right, 

 a following 2 / 7 -spiral turns to the left; the evolution of the positions may 

 be indicated as follows: 



2 ^ 2 r m, v 2 m. v 2 / m s 2 m v 2 r m v 2 m ^ 2 / 5av__v 2__ 



where r and I signify right and left respectively. 



The transition from one spiral to another is without any intermediate 

 positions; but when passing from a whorl to a spiral, we always find a 

 lot of different intermediate positions; as examples see in Fig. 5 the 

 transition from 2 / 8 to 2 / 9 , and in Fig. 7 from 2 / 6 to 3 / 8 . In Fig. 6 is shown 

 the position of the leaves at the base of some lateral shoots — in the main 

 the same as the position of the leaves on the sexual shoots (Figs. 12, 13, 

 14, 17 and 20). 



In Denmark the flowering takes place in March or April, and 1 — 3 

 weeks later the evolution of the vegetative shoots begins and when these 

 vernal shoots are completely developed, the longitudinal growth stops 

 for a time; but in June the development of another section of the annual 

 shoot begins, which might be called the »summer shoot«. All the 

 shoots of an Empetrum plant are developed in two periods. The 

 two sections of an annual shoot might be distinguished by the following 

 relative characters: 





Lateral 

 shoot 



Leaves 

 of basis 



Colour of the 



cortex 

 (in winter) 



Form of the 

 leaves 



Colour of 

 the leaves 



Direction of 

 the leaves 



Position of 

 the leaves 



Vernal 

 ehoot 



missing 



brown 

 bud-scales 



brown 



pointed 

 thin 



dark 



obliquely 

 erect 





Summer 

 shoot 



sexual and 

 vegetative 



green 



red 

 (or green) 



obtuse 

 thick 



light 



often 

 vertical 



often 

 another 



