One ton of kelp may give 500 lbs. pure potassium salt 

 and about 3 lbs. of iodine, worth from 20 to 25 dollars. 



The source of the potassium lies in the fact that sea water 

 contains about 1/25 of 1% of pure potassium. 



As fertilizers the marine algae have been extensively used 

 for a "top dressing." They enrich the soil and produce a vigor- 

 ous growth of corn, potatoes, turnips, clover and pasture. 



Their fertilizer value is due to the great amount of potas- 

 sium and nitrogen compounds that they contain. There is a 

 lack of phosphates. The nitrogen is not available until decom- 

 position and putrefaction have taken place. 



As progress is made in the utilization of these gardens of 

 the sea there is danger that the supply be exhausted by waste- 

 ful methods. The undeveloped or partially developed natural 

 resources of the ocean are becoming more important and are 

 certainly worthy of consideration with other natural resources 

 in connection with the question of conservation. 



Lines that may be pursued leading to a better conservation 

 of the ocean's vegetable resources are: (1) acquaintance with 

 these plants and their characteristics; (2) knowledge of their 

 means of propagation and regeneration; (3) the relation of the 

 seasons to their growth and development; (4) the physiology 

 of their food relations; (5) their distribution and the factors 

 concerned with distribution and orientation in different depths 

 of water ; (6) care that poisonous or otherwise injurious ma- 

 terials do not pollute the ocean water where these are abun- 

 dant. 



The "kelps'' are the most prominent marine plants on the 

 southern California coast that are utilized. Of these Macro- 

 cystis pyrifera, Egregia laevigata, and Nereocystic lentkiana are 

 the most common. Particular attention has been given to 

 Egregia of the adjacent coasts, and there is indication of sea- 

 sonal effect, as a new growth has been observed to begin about 

 the last of February oj- first of March. 



Where the waves had broken off the main part of the 

 plant, regeneration was observed to be taking place at near the 

 hold-fast. In this alga growth takes place from the upper po£- 

 tion of the stipe and regeneration proceeds rapidly from this 

 point. 



Also yo'ung plants of Egregia were found in March, just 

 getting a foothold on the rocks. 



Rigg, in a discussion of regeneration in the kelps, divides 

 it into renewal of blade and restoration of entire plant. Ac- 

 cording to his discussion, the blades are renewed from the 

 interior, and renewal of the plant from injury is from the ac- 

 tively growing region. He suggests that a part only of a kelp 

 bed be cut at once, to give it a better chance for restoration. 



The question of pollution of certain portions of the sea 



42 



