9-; 9, 



at present prices nearly $40,000,000." It is to be noted that this 

 is more than three times the amount of potash now used annually 

 in the United States. Mr. Milton Whitney, the chief of the 

 Bureau of Soils, adds: "Moreover, it should be perfectly feasible 

 to cover most, if not the entire, cost of production of this vast 

 'crop' by the iodine and other by-products produced simul- 

 taneously." Dr. Frank K. Cameron, under whose special direc- 

 tion the work has been carried on, sums up the potash situation 

 in the United States as follows: 



"In so far as present information goes, the Pacific kelp groves 

 are and probably will remain by far the most important American 

 source of potash. In fact, if carefully and skillfully husbanded 

 they promise to approximate and perhaps even surpass, in im- 

 portance and value, the famous Stassfurt mines. Alunite, 

 important as it is, falls far behind." 



The great kelps of the three genera chiefly considered live 

 attached to the bottom in water that is mostly from 10 to 100 

 feet in average depth, whence they grow to the surface, forming 

 extensive beds or groves. Detailed methods of cutting or har- 

 vesting in a practical and economic way have not yet been fully 

 worked out, but it is believed that the problem offers no insuper- 

 able difhculties. Nereocystis and Pelagophyciis, though some- 

 times growing to a length of from 60 to 150 feet, are annuals, 

 while Macrocystis is apparently a perennial plant, and these facts 

 will have to be considered in devising practical methods of har- 

 vesting and conserving the kelp groves. Professor George B. 

 Rigg (Appendix L, Ecological and economic notes on Puget 

 Sound kelps, pp. 179-193) finds that in Puget Sound the spores of 

 Nereocystis are for the most part ripened and set free by July 15 

 and that after that date it would be possible to harvest this kelp 

 without interfering with the next season's crop. 



Besides the special papers already mentioned. Senate Docu- 

 ment No. 190 includes a botanically important and useful paper 

 on "The kelps of the United States and Alaska" (Appendix K, 

 pp. 130-178) by Professor William Albert Setchell, embracing a 

 general morphological and ecological account of the Laminaria- 

 ceae, keys to the genera and species of both the Atlantic and 

 Pacific coasts, and an interesting resume of the past and present 



