1916 



Fallisj on Laminariaceae 



139 



grew faster than young ones, likeW because the growing region is longer. 

 Cutting off the tip apparently did not materially effect the growth so 

 long as the basal 5-50 cm. of the blade was left {table 1.) 



Table 1. Shozcing the growth of plants cut to different lengths. 



Costaria 



18 

 18 

 18 

 18 

 18 



cm. 



21 



16 



12.2 



17.5 



12.5 



10 

 20 



40 

 50 



cm. 

 23.0 

 16.3 

 12.5 

 17.9 

 12.9 



cm. 



9.5 



28.1 



49.7 



72.7 

 81.6 



(.m. 

 2. 

 .3 



A 



.4 



cm. 

 4.5 

 18.1 

 29.7 

 32.7 

 31.6 



Laminaria 



38 

 38 

 38 

 38 



cm. 

 1.6 

 4.2 

 5.0 

 7. 



cm. 



S 

 10 

 20 

 40 



cm. 



1.8 

 4.5 

 5.3 



7.5 



cm. 



55.9 



63.9 



122.6 



82.1 



cm. 

 50.9 

 53.9 



102.6 

 42.1 



Alaria 



37 

 37 

 37 

 37 

 37 

 37 



cm. 

 60.3 

 56.3 

 19.0 

 28,0 

 40.0 

 69.0 



cm. 

 5 

 10 

 20 

 40 

 80 



110 



cm. 

 61.2 

 57.4 

 21.0 

 29.8 

 41.3 

 70.4 



cm. 



52.4 



65.2 



89.9 



126.3 



200.1 



311.7 



cm. 

 .9 

 1,1 

 2.0 

 l.S 

 1.3 

 1.4 



cm. 

 47.4 

 .■5.2 

 69.9 

 86.3 

 120.1 

 201.7 



Agariim 



20 

 20 

 20 

 20 

 20 



cm. 

 1.3 



4 

 2.6 



cm. 



5 

 10 

 20 

 30 

 35 



cm. 

 1.4 



2.5 

 7.2 

 4 

 2.7 



cm. 

 10.2 

 16.3 

 24.4 

 36.1 

 46.8 



cm. 

 .1 



.0 



2 



!o 



.1 



cm. 



,2* 

 ,3^ 

 4.4 

 6.1 

 11.8 



Not only will the plants grow when the holdfast is removed and the 

 stipe shortened, but even small portions of the growing region of the 

 blades will grow when cut out, tacked to a submerged raft, and held in 

 place by strips of cotton. Other pieces too small to be kept secure by 

 such a method were tied up in a cheese cloth bag and submerged at the 

 side of the raft. Even pieces as small as 1 mm. square, showed some 

 growth, and many of those slightly larger, more than doubled their length 

 in 10 days {table 2). Each of these pieces was cut from the basal grow- 

 ing portion of the blade. Other pieces corresponding in size cut from near 

 the tip of the same blades — as for example 100 cm. from the base in 

 Alaria — sliowed no increase in length or breadth. Small pieces of Ci/ma- 

 there showed only a very slight growth even when selected from the base 

 of the blade. 



The growth of the stipe is extremely slow compared with that of tlie 



