22 



the same appearance, a couclusion I draw from the observations made off the east 

 coast of Falster (fig. 4) aud in Faxe Bay (see the Table of measnrements, p. 46). 

 The length of the leaves is here not above 83 cm. aud the breadth between 3 

 and 4.5 mm. 



Along our coasts the grass-wrack does not form large, connected growths 

 neither in the open Kattegat nor in the Baltic; the situation is appareutly not verj' 

 suitable aud this may be due to the want of shelter and the poor soil. 



As soou as there is a little shelter the grass-wrack appears in large quan- 

 tities aud the single plant grows stronger in all respects. In the Table of measure- 

 ments (p. 42 — 46) we find even transitions from the narrow-Ieaved Kattegat-Zostera 

 to the broadleaved Mud-Zostera. The Zostera in Nissum Bredning, in Samso Belt, 

 aloug the north coast of Zealand and partly in the Smaaland Waters furuishes 

 examples of such intermediate stages, and we nearly always find the bottom given 

 as firm. It is generally a dark-coloured sand bottom soil the colour of which is 

 due to no .small quantities of organic materials mixed with sand — in other 

 words, a soil where there is certainly a considerable wave-motion, but yet where 



a portion of the organic particles has 

 been deposited and has fertilized the 

 sand. The measnrements from Smaa- 

 land waters (see Table p. 45) give a 

 fairly clear picture of the Zostera's rela- 

 tion to the kind of bottom soil; the first 

 two stations (1 — 2) were taken in Fæmo 

 Sound and thereabouts; the soil is here 

 soft and the leaves of the Zostera reach 

 a length of 88 — 138 cm. and a breadth 

 of 6.b — 7 mm.; the other stations were 

 in more open water and have a more 

 solid soil; the length of the leaves is 

 liere mostly below 100 cm. and the 

 breadth between 4.5— 6 mm. (see fig. 2). 

 The other conditions being verj' similar, 

 it appears from this that the different 

 growth of the grass-wrack is due to the 

 different bottom soil and the conditions 

 Avhieh arise from these. 



^\'e tiud a typical vegetation of 

 Mud-Zostera in Nyborg Bay and the 

 measnrements given above (pp. 8 — 9) of 

 Zostera piants throughout a whole year 

 provide an excellent material for the 

 purpose of elucidatiug the appearance 

 of the grass-wrack, wiien it grows on 

 the soil which snits the plant best and 



Fig. 4. Two leafbearing .shoots of the snialMcavod Zostera i •, • -i i • i i i !■ 



from the Baltic ; at .T the blade i,s alioiit lo separate from Wncre it rcaches U.S lughcst dcgree 01 



the sheath. i , , 



(Finn, slony grouncl, ofl' Tromnæs, Falster 51/2 (•«., ."j. VIII. 01.) tleVelOpment. 



