142 Puget Sound Marine Sta. Pub. Vol. 1, No. 13 



Erosion of the apex of the blade follows next." The rate of growth in- 

 creases very rapidly from the base upward for a short distance, then de- 

 creases abruptly, then more slowly until at the end of the blade no growth 

 at all is observed (Figs. 4, 6). 



It was found that the place of maximum growth in Egregia was not 

 even near the base of the strap-shaped branches, but near the ends of 

 these branches where they broaden out into the wrinkled blades, and in 

 the lower part of these blades. Apparently the rounded strap-shaped part 

 corresponds to the stipe of the other kelps, while the flattened broader 

 parts that gradually emerge from the former correspond to the blades 

 (Figs. 16, 17). This confirms Ramaley's (5) view of homologies. In the 

 upper portions of these blades of Egregia, where they are firmer and not 

 so pliable, no growth occurs; just as in the upper portions of the blades 

 of other Laminariaceae there is no apparent growth. In this species the 

 transition between stipe and blade is very gradual. Three blades with 

 some stipe attached were left to grow for 8 days with the following results : 



Original 35 cm., became 41.5 cm., increasing 6.5 cm. 

 Original 65 cm., became 73.1 cm., increasing 8.1 cm. 

 Original 250 cm., became 281.7 cm., increasing 31.7 cm. 



Two other Egregia plants were grown for 8 days. These had the blades 

 and holdfasts cut off, and were therefore mere stipes. They showed the 



following : 



Original 170 cm., became 177 cm., increasing 7 cm. 

 Original 460 cm., became 463 cm., increasing 3 cm. 



Since the stipes grow so little it is evident that most of the growth is in 

 the blades and perhaps in tlie stipes where they grade into them. 



To show more exactly the region of elongation, kelps of various species 

 were measured into spaces from the base of the blade up, and in Egregia 

 from the base of the blade down also. These kelps were then permitted 

 to grow from 11 to 41 days and the spaces measured. The results are 

 given in table 3. That the growth is mostly near the stipe is very evident. 



The rate of growth for the 6 species experimented with varied with 

 the individual and the species. The average daily growth was as follows: 

 Laminaria, 2.85 cm.; Alaria, 2.23 cm.; Costaria, 2.04 cm.; Egregia, .98 cm.; 

 Cymathere, .81 cm.; Agarum, .58 cm. The results of the rate of growth 

 obtained for Agarum, Cymathere and Egregia are very unsatisfactory, as 

 the conditions of submergence, aeration, etc., were not the most favorable 

 for these plants. The growth of Cymathere was very slow for a plant of 

 its length. It is quite possible that its growth may have been slow even in 

 its natural habitat, at that time of the year; or it may be that the rapid 

 growth was earlier in the season; or possibly it is not an annual plant. 

 One would suppose, however, that taking the plants from a depth of from 



