915 



Fallisj on Nereocystis 



Table 7. Showing growth of small pieces cut from center of frond. 



A rather peculiar fact observed is that the kelp fronds grow more 

 rapidly on some days than on others. According to observations the 

 greatest grovi^th was on those days of most windy weather. This was 

 probably due to the fact that the water was moved about and better 

 aerated. According to Frye (1), Setchell (4) and Rigg (3) kelps will 

 not grow in quiet waters, but are confined to situations where subjected 

 to strong tidal currents. 



Without the wind records during the time the observations were 

 made on the growth of the fronds, or any knowledge of how much of this 

 growth took place during the night when it may or may not have been 

 windy, no definite conclusion can be drawn. However, the writer expects 

 at a later date to collect data with regard to wind effects upon the growth 

 of Nereocystis. 



Different fronds grow at different rates. To show this the fronds 

 on a plant were trimmed to a length of six inches, left to grow for a 

 time, and again measured ; it was found that they then varied from 24 to 

 36 inches in length. This is an extreme difference in the rate of growth 

 in the {)roportion 3 :5. It was usually the outer frond that grew most 

 rapidly. 



The two edges of the same frond grow at different rates. The outer 

 margin grows most rapidly. The central region grows more slowly than 

 the margins. These variations in the same frond account for the ruffling 

 of the margins, and the curvature of the frond. 



SUMMARY 



1. Nereocystis will grow as well when loosened from its foothold 

 on the rocks, so long as it is not carried into unfavorable situations, e. g., 

 washed ashore. 



2. The holdfast serves only to fix the plant. 



3. Not only the holdfast but the stipe including the bulb are un- 

 necessary for the growth of the fronds. 



4. The fronds may be cut into very small pieces and each piece grow 

 independently. 



