2 BULLETIN 1191, U. S. DEPARTMENT OF AGRICULTURE. 
publication is deemed imperative even in its present form. Any 
further details to be established must be left for future investigators. 
While this paper is essentially a study of plants, an activity nor- 
mally coming within the sphere of the Bureau of Plant Industry, 
it is published by the Bureau of Soils because it has been through 
that bureau that the investigation of the economic utilization of the 
giant kelps has been prosecuted. 
Other papers of series—This paper is offered as a part of a series 
dealing with the industrial utilization of kelp. Other papers of 
this series already published are: The Kelps of the United States 
and Alaska, by William Albert Setchell; Ecological and Economic 
Notes of Puget Sound Kelps, by George B. Rigg: The Kelps of 
the Central California Coast, by Frank M. McFarland; The Kelps 
of the Southern California Coast, by W. C. Crandall; Brief Notes 
on the Kelps of Alaska, by Edward ‘C. Johnston; The Composition 
of Kelps and the Technology of the Seaweed Industry, by J. W. 
Turrentine; A Discussion of the Probable Food Value of Marine 
Alge, by Carl L. Alsberg, published as appendices to The Fertilizer 
Resources of the United States, Senate Document No. 190, Sixty- 
second Congress, second session, December 18, 1911; Pacific Kelp 
Beds as a Source of Potassium Salts, by Frank K. Camreton: The 
Kelp Beds from Lower California to Puget Sound, by W. C. 
path So inal 
Crandall; The Kelp Beds of Puget Sound, by George B. Rigg; The | 
Kelp Beds of Southeast Alaska, - by T. C. Frye; The Kelp Beds of 
Western Alaska; by George B. Rigg, published as parts of Report 
No. 100, Potash from Kelp, Bureau of Soils, April 10, 1915; Potash 
from Kelp: The Experimental Plant of the United States ‘Depart- 
ment of Agriculture. Preliminary Paper, by J. W. Turrentine and 
Paul S. Shoaff (J. Ind. Eng. Chem. 17, 864, 1919); Note on the 
Distillation of Kelp, by J. W. Turrentine (Proc. 8th Internat. Cong. 
Appld. Chem., 75, 313); The Experimental Distillation of Kelp at 
Low Temperatures, and The Preliminary Examination of Kelp 
Distillates, by G. C. Spencer (J. Ind. Eng. Chem. 72, 682 and 786, 
1920) ; Continuous Countercurrent Lixiviation of Charred Kelp, by 
J. W. Turrentine and Paul 8S. Shoaff (ibid, 73, 605, 1921): The 
Applicability of Kelp Char as a Bleaching and Purifying Agent, by 
J. W. Turrentine and H. G. Tanner (ibid, 74, 19, 1922) ; The Decol- 
orizing Action of Adsorptive Charcoals, by H. G. Tanner (ibid, 14, 
441, 1922); The Manufacture of Potash Salts, by J. W. Tmrent ite 
H. G. Tanner, and P. S. Shoaff (ibid, 75, 159, 1923): Certain 
Equilibria Used in the Manufacture of Potassium Chloride from 
Kelp Brines, by J. W. Turrentine and H. G. Tanner (in press). 
LIFE HISTORY OF MACROCYSTIS PYRIFERA. 
SPORES. 
.Macrocystis reproduces by means of minute “swarm spores.” 
These are borne on the slender, short-stemmed ay es found densely 
clustered at the base of the plant. These leaves, or sporophyls (fig. 
1), may be deeply grooved or perfectly plane; and the spore-bearing 
areas, or sori, may be either continuous, completely covering both 
surfaces, or confined ‘to the grooves. Millions of spores are liber- 
ated during a year, by each sporophyl. They are olive gréen in 
