24 



ments, made ou piants from various depths in a quiet creek in Nexelø Bay on 

 the north coast of Zealand (Table No. 2); it is in sharp contrast to tlie measure- 

 ments from the other stations on the north coast of Zealand, for these all come 

 from the opeu water. Typical Mud-Zostera moasureraents are further giveu in the 

 Table for the Lim Fjord, east of Livø brickfield and off Nykjøbing Mors (Limfjord, 

 Nos. 7 and 9), for the waters between Samsø and Jutland (No. 1 — 2) and off Nysted 

 (Guldborgsund, Nos. 5 — 6). The leaves of the grass-wrack in Langeland Belt (Great 

 Belt and Langeland Belt, Nos. 2 — 4) are a little narrower but of the same length, 

 altliough the bottom soil is mostly firm here; it is however not the ordinary sand 

 bottom but stony with rich algal vegetation, where the fine nutritious material has 

 been able to settle between the stones. This exception is au excellent confirmation 

 of the rule that the length and breadth of the Zostera leaves, i. e. the size 

 of the grass-wrack, is more dependent on the nature of the bottom soil 

 than on the depth in which it grows, though vvithiu certain limits, siuce the 

 plant never grows large and broad-leaved in quite shallow water. K. Techet's 

 statement (1. c, p. 19) as to richer growth of the Zostera in Trieste Golf near the 

 harbour, where of course the sea bottom and the sea water are richer in organic 

 matters than at a further distance off, agrees well with my observations. The 

 Zostera plauts are much like land piants in regard to the importance of the nature 

 of the ground, and not so much like most other marine piants, the algæ. We 

 usually find it stated that it is the depth, which is the most important, but this 

 is uot quite correct as showu here. It is thus not entirely in accordance with the 

 facts, when P. Magnus') states that the leaves of the grass-wrack in the Western 

 Baltic become larger and broader at greater depths, or when E. Warming-) savs in 

 his »Strandvegetatiou« : »The size of the Zostera-leaves is dependent on the depth 

 etc«; this author adds however a little further ou in the same work (p. 192): 

 »The Zostera belt is divisible into two, a broad-leaved and a uarrow-leaved kind, 

 connected with the depth and perhaps also with the nature of the bottom 

 soil, as far as this may be firmer in shallower water and less permeable 

 for the roots and root stocks; neither is it perhaps so rich in nutriment«.-^) 



') Ber. d. Komm. zur wiesensch. Hnters. dentscher Meore in Kiel, 1872—73, p. GG. 



') Danslv Plantevækst. I. Strandvegetiition, 1906, ji. 186. 



"1 I am rosjionsibk' for the translation from tlio Danish and for tlu' empliasis. 



