longitudinal striugs some stripes more or less brokeu and often like a string of 

 pearls are visible; agaiust the light they are dark, but with the light falling upon 

 them they are whitish or light green, being covered by the outer green skin of 

 the leaf; these are rather long and very narrow cavities filled with air. It is 

 easily ascertained that they contain air by holding a bit of leaf in water and 

 presssing it between two 

 fingers; air bubbles rise from it. 



In order to learn liow 

 many leaves are produced by 

 the Zostera in the course of 

 a year, I have made a great 

 many measurements. It is 

 not easy to determine how 

 much the plant grows and 

 liow many leaves it develops, 

 as, apart from the length, 

 the leaves are alike all the 

 year round and at anj' rate 

 apparently have no resting 

 period like our land piants, 

 and further, as it is impos- 

 sible to mark the root-stock 

 of a certain ]ilant on its na- 

 tural plaee at the bottom of 

 the sea and inspect it in 

 order to follow its growth. 

 Nor has the eelgrass like 

 our trees any fixed rule of 

 branohing which tells us that 

 normally the sho<it is branch- 

 less the first year and gets 

 branched the next, so that 

 the age of a Ijranch may be 

 determined. 



I have tried to clear 

 up these questions by inve- 

 stigating a certain number 



of shoots collected at a certain place and depth once a month throughout a 

 whole 3'ear. 



I am iudebted to Dr. C. G. Joh. Petersen for kindly euabling this inves- 

 tigation to be carried out, as it wonld have been quite impossible for me perso- 

 nally to have collected the material month by month. In 1901 the Biological 

 Station had its liead-quarters at Nyborg, and I chose for the investigation a place 

 in Nyborg Fjord off Holckenhavu where I found a rich growth of grass-wrack 

 from 372 fffis. to inshore (Vi — V'2 fms.). At a depth of Sy., — 2 fms. the bottom 

 was soft, whereas it was hard at IV2— Vi fins., the grasswrack being accordingly 



2 



Kig. 2. .-1, Leaf-bearing shoot; * shows the place where the blade has 



fallen off. B, Flower-bearing shoot from the same place. (Sand bottom, 



Smaalaod waters, Omo Bank, oa. 2 fms., 7. August 1901). 



