Growth of the Fronds of Nereocystis Luetkeana 



Annie L. Fallis, 

 University of Washington, Seattle. 



Concerning the growth of the fronds of Nereocystis very little has 

 been carefully and accurately determined. Particularly concerning the 

 rate of growth and just where in the frond the growth occurs, very in- 

 sufficient information of any certain nature can be found. Frye (l) reports 

 that the growth of the plant is very rapid and more especially in the 

 spring. However, no statement is made with regard to the growth of 

 the fronds alone, only with regard to the growth of the plant as a whole. 

 In the same way Setchell (2, 4) speaks of the size of this kelp and its rapid 

 growth, but gives no definite record of the growth of the fronds alone. 

 It was for this reason that during the summer of 1914 at the Puget Sound 

 Marine Station at Friday Harbor experiments were undertaken under 

 the direction of Dr. T. C. Frye, to determine if possible some of these 

 facts with certainty. 



The experiments were carried on in four different beds of Nereo- 

 cystis off the coast of San Juan and Brown Islands. Strips of white 

 cloth marked with different colors and numbers were used in labeling. 

 Observations and measurements were taken from day to day. The first 

 experiment was to find out whether the plants would grow if detached 

 from the rocks at the bottom of the water, and the effect upon the fronds 

 of the removal of parts or all of the stipe. Setchell (4) says: "The Lamina- 

 riaceae, like other fixed algae, depend upon a firm foothold, and are 

 found affixed to rocks, stones, shells, wood, iron, and to other large algae. 

 * * * * While some of the kelps, like Macrocystis, Pelagopfiycus, Nereo- 

 cystis, Alaria fistulosa, etc., float for long distances, they make no growth 

 except when attached, and perish when torn away from their substrata." 



To test this inability of Nereocystis to grow when torn from its at- 

 tachment, plants were loosened from the rocks, shells, or whatever the 

 holdfast had been attached to, and tied to the bulbs of naturally anchored 

 ones. Otherwise they were left freely floating. The conditions under 

 which they were left were various. Some were left attached in their nat- 

 ural condition; others were pulled loose and anchored by the holdfast; 

 from otliers three feet of the basal portion was removed ; from some rather 

 young plants more than half the stalk was removed; from other plants 



(1) 



