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off Djursland small spots of Zostera have been found here 

 and there. 



2. The sea between South-Sjælland and Lolland- 

 Falster and the sea between Fyen and Æro and Lange- 

 land are covered with very extensive meadows of Zostera. 



The maximum depth depends on the transparency 

 of the sea water, as will be seen from the following experiment: 

 a white disk, about 25 □ cm., was affixed to the lead and laid down 

 with it in many places; when it disappeared, we had also always 

 reached the limit of the Zostera-vegetation. It is to be remembered 

 that the experiments have been made in the summer, at other 

 seasons the transparency of the water may be different. 



II. The biology. 



In summer the Zostera bears 4—5 (3—6) fullgrown, green 

 leaves. It grows both in sandy and in muddy bottom; in sandy 

 bottom the length of the leaves (incl. the sheaths) of the vegetative 

 shoots reaches only 50 — 80 cm. with a breadth of the blade of 3 — 

 4,5 mm., while in muddy bottom the figures are respectively 160 — 

 230 cm. and 6 — 8 mm. The length of the sheaths is in sandy 

 bottom 12,5 — 17,5 cm., in muddy bottom 35 — 65 cm. The breadth of 

 a leaf is nearly proportional to its length, and as many leaves are 

 broken, it is more practical to use the measurements of the breadth, 

 when treating the more or less rich development of a Zostera- 

 vegetation. 



In sandy bottom the Zostera is always rather small 

 and narrow-leaved, also at its deepest places, e. g. in the 

 open Kattegat and in the Baltic Sea off Falster. 



In muddy and sheltered places it reaches its richest 

 development from ab. 3 m. dovvn to 10 m. and there is no 

 distinct difference in the development of specimens growing at 

 3— 5 in. and in others at 8—10 m. Consequently the develop- 

 ment (i. e. the largeness and breadth of the leaves) does not 

 depend on the depth in which the plant grows, but 

 depends on the character of the bottom (the soil). In 

 sandy bottom the breadth of the leaves varies from 1,5 to 4,5 mm., 

 in muddy bottom from 5,5 to 8 mm. 



The Zostera loses its long summer leaves in the 

 autumn in that way, that the leaf breaks in the point where 

 sheath and blade meet; the blade becomes driving and the 



