Historic, archived document Do not assume content reflects current scientific knowledge, policies, or practices. Washington, D. C. Vv - December, 1923 POTASH FROM KELP EARLY DEVELOPMENT AND GROWTH OF THE GIANT KELP, MACROCYSTIS PYRIFERA By R. P. BRANDT, Cooperator of the United States Department of Agriculture with introduction by [J. W. TURRENTINE, Scientist in Soil Laboratory Investigations, Bureau of Soils Life History of Macrocysiis pyrifera Growth with reference to environment Seasonal variation in condition of kelp beds Destruction by natural agencies Methods and effects of harvesting Summary Literature cited WASHINGTON GOVERNMENT PRINTING OFFICE Pe Ee IP Pe PE Ry A ps ee ae ee Oe Washington, D. C. December, 1923 - POTASH FROM KELP: EARLY DEVELOPMENT AND GROWTH OF THE GIANT KELP, MACROCYSTIS PYRIFERA. By R. P. Branpt, Cooperator of the United States Depariment of Agriculture. With Introduction By J. W. TurrentTINE, Scientist in Soil Laboratory Investi- gations, Bureau of Soils. CONTENTS. Page. Page. teil ti 1G. oe A ae Se ee ee 1 | Destruction by natural agencies____ 29 Life history of Macrocystis pyrifera_ 2 | Methods and effects of harvesting_. 35 Growth with reference to environ- wo Te bebe seal 38 eae oe 40 _ || aS eS eee nome See Seeds Ne oO it diterture cited 0s iss i ee 40 Seasonal variation in condition of ibibo ci: eo Ee ee ee 28 INTRODUCTION. In the paper here presented are results obtained by Dr. R. P. Brandt in two years’ study of the life history of the giant kelp, _ Macrocystis pyrifera. The work on which this paper is based was -earried on principally at the Scripps Institution for Biological Research under the supervision of Dr. William E. Ritter, director of the institution, and particularly of Prof. W. C. Crandall, business manager and scientist of the institution and likewise a collaborator of the United States Department of Agriculture. The researches here were undertaken as a part of the broader study of the economic utilization of the giant kelps of the Pacific for the manufacture of potash and other chemicals, for which work the Congress of the United States made a number of appropriations, principally for the erection and operation of the experimental kelp-potash plant at Summerland, Calif., as operated by the Bureau of Soils of the United States Department of Agriculture. An active collaboration Was maintained between the work carried on by Doctor Brandt at the Scripps Institution and that at Summerland, and the economic _ phases of his studies were accordingly given emphasis. The unfor- tunate and tragic death of Doctor, Brandt brought his investigations to an immature close. The paper here presented accordingly does not represent an exhaustive research on the subject studied, but never- theless conveys so many facts of interest and importance that its a 56751—23-——1 1 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 POTASH FROM KELP. 3 color.-and differ but little in appearance from the spores of some of the green seaweeds. The diameter varies from about 2 to 6 ‘microns and the length from about 4 to 6 microns; 1n other words. it would take 200 or 300, placed end to end, to span a pin- head. They vary in form from nearly globular. to slender spindle- shaped. The spores borne in the autumn are mostly of the spindle- ' shaped type, are small, only slightly colored, and ue highly motile. The large globular spores appear mainly in midwinter. They are deeply colored, very sluggish, and soon come to rest. The cilia by means of which the spores swim can scarcely be distinguished in living spores under the ordinary - powers of the microscope, but they are very slender, ~ and attached either at the apex or on the side of a spore. PLANTING IN AQUARIA. ‘ | Spores have been repeatedly germinated in the _ laboratory and the sporelings kept alive for a _ period, sometimes of several months. For success- - ful germination a cool, well-lighted room is re- _ quired. A glass vessel is the best container for the culture, on account of its permitting full penetra- tion of light. If it is possible, a constant stream of | sea water at ocean temperature should be kept run- - ning into the vessel, or if there are not the means for keeping a stream running, the water should be _ changed frequently and, in addition, should be fre- _ quently agitated to work in air. With suitable con- ditions, sporelings may be had by placing a few fresh, mature sporophyls in the culture vessel. _ Whether the spores are good or not can quickly be 4 found out by scraping off a little of the soft tissue _ near the tip of a sporophyl and examining it under _ the microscope. Healthy spores float out and soon may be seen swarming about in a manner resem- bling bees. Within an hour after planting the _ sporophyls the water takes on a brown color as y _ though full of fine mud. This color continues for a day or two, but finally the water clears if rie. 1.-Sporophyi. there is good circulation. This subsequent clear- Sh2ded, areas are ing is due to many spores coming to rest or at- “ipe sorus at the . ‘ tip, young sorus taching themselves to a fixed object. The spores developing’ at the ~ come to rest sometimes in a few minutes; at other — Dase, and Jensthe _ times they may swim for 24 hours. Currents have — stows. One-half much more to do with their wide dissemination than >” _ has their own motility, but the latter probably enables them to get _ out from the shade of the parent plant. __ When the spores come to rest they take on a globular form, and _ their walls become thick and mucilaginous, enabling them to cling _ to the glass walls of the culture vessel or to any other object with _ which they may come in contact. If there is no circulation in the culture vessel, the spores become the prey of bacteria within two 4 BULLETIN 1191, U. S. DEPARTMENT OF AGRICULTURE. days, no matter what precautions are taken. On the other hand, with good circulation and aeration the ‘walls of the vessel soon take on a rich brown color, especially where the air supply is more plentiful. The sporelings have slender, club-shaped germ tubes. (Fig. 2, C.) In a healthy culture spores may be found germinating six hours after the planting of the sporophyls. Many spores floating on the surface of the water seem to germinate more slowly, and those that attach themselves to the sides of the vessel within 4 inches or less of the surface seem to grow the best. EARLY STAGES. The examination of millions of sporelings has not furnished con- clusive evidence of sexuality. Young sporelings have been found with their club-shaped ends in contact, but the cell-wall was still in- tact between the two plants. They were always outnumbered more than 1,000 to 1 by similarly shaped plants whose tips were not in con- tact, so it appears to have been a case of chance contact of independ- ent plants, and not of fusion of germ-tubes. The germ-tubes usually consist of a single cell for the first week or two. Gradually the ter- minal portion increases its diameter until many sporelings assume a form resembling dumb-bells. The color-bodies, or chromatophores, migrate to the enlarged end, leaving the old spore and the slender base of the filament colorless. A number of recent observers have regarded these plants as male or antheridial plants, but the author has found no satisfactory evidence that they are. Minute olive- green globules have often been seen in sporelings 1 or 2 weeks old, and also moving about in the water in which the sporelings were mounted for study, but they have never been seen moving within the filaments preparatory to escaping, as the sperms move within the antheridia of mosses. Furthermore, these bodies that might be regarded as sperms fre- quently occur in sporelings that show no thickening. They are also commonly associated with an undivided part of the chromatophore. They have also been seen in plants that differed greatly in form from those regarded as antheridial, and Pelagophycus spores have been seen to break up into such bodies even before assuming the globular form of resting spores. Their occurrence, therefore, seems merely to indicate the death and decay of sporelings. Very commonly a cul- ture makes a good growth for two or three weeks and then suddenly dies out. The spores seem to germinate readily and pass the first stages under conditions not at all favorable for further development. With good circulation and aeration at a temperature of 14° to © 16° C. the sporelings continue to grow for two months or more. The enlarged and condensed ends of the dumb-bell shaped sporelings con- tinue to enlarge and soon begin to divide, by cross walls, to form chains of cells. The color, hitherto olive-green, becomes the char- — acteristic brown of Macrocystis. The filaments may become 5 to 10 cells long and they often branch extensively. (Fig. 2, D.) These may be gametophytes or sexual plants, but none has been found giv- ing rise to leafy kelp plants, nor has a structure been found in one of them that could be identified as an oogonium or egg cell. They seem instead to form various fantastic little plants and then die. ‘Typical kelp plants, or sporophytes, as they are called by those who believe them to be of sexual origin, arise from what often ap- POTASH FROM KELP. Fic. 2.—A.— Spores stained in methylin blue. Drawn with a camera lucida, using a No. 10 eyepiece and a 1-mm. oil-immersion lens, B to J.—Sporelings in various stages of development. # and @ stained in methylin blue and drawn with a camera lucida, using a No. 10 eyepiece and a 4-mm. dry objective. Remaining drawings reconstructed from sketches of living specimens. a=proembryo; b=embryo ; r—=rootlets or rhizoids. A, more highly magnified. 6 BULLETIN 1191, U. S. DEPARTMENT OF AGRICULTURE. pear to be single isolated cells. (Fig. 2, E and F.) Careful exami- nation of isolated specimens, however, reveals the presence of one or more additional cells. The cell which is to give rise to the new plant or embryo is much larger than the other cells of the filament in which it occurs. It-also develops denser, more deeply colored con- tents. The appearance and behavior of this cell, which may be ‘alled the proembryo, strongly suggest sexual origin, but that it is of this nature awaits proof. As the proembryo approaches ma- turity, it takes on the form of a truncated cone attached to the sub- stratum by the expanded, thin-walled base. The walls next the free end b-come very thick, but remain thin over the summit. The cell contents become congested at the free end of the cell, chromatophores becoming longitudinally oriented. (Fig. 2, G and H.) The pro- toplast now begins to withdraw from the base of the cell, a new cell wall is formed around it, and the extrusion of the embryo takes place. The thin-walled summit of the proembryo opens and the now spindle-shaped embryo is thrust out by the rapid absorption of water. The embryo is not forced violently out, but remains with its tapering base within the thick-walled mouth of the empty pro- embryo, which serves as a holdfast until the embryo can form rhizoids or rootlets. (Fig. 2, I.) A cross-wall is formed, dividing the embryo into a two-celled structure at the time when it is being extruded. Other cross-walls appear in rapid succession until the embryo is 5 or 6 cells long. The first rootlet or rhizoid now buds out from the base of the embryo. grows down through the empty proembrvo cell, and attaches the embryo to the substratum. Additional cross-walls are formed in the embryo until it is 7 or 8 cells long, and then longitudinal walls begin to appear. Additional rhizoids, always consisting of a single hairlike cell, bud out above the primary one, increasing the grip of the young plant as it grows. (Fig. 2, J.) By the time the young plant is 12 to 15 cells long, the region of most active growth seems to become located near the base. Owing to difficulties experienced in growing plants in the laboratory, the later stages up to the origin of the stipe must be omitted for the pressnt. Plants have been brought to the embryonic stages in only a few instances, and when these stages are attained, the plants are much more easily dis- lodg d and lost than pre-embryonic plants. Thus, good cultures have disappeared completely while they were believed to be making a thrifty growth. From the results obtained, however, an estimate can be made of the time required for the different stages, and a notion can be formed of the conditions under which the young plants develop. Spores will germinate and live for many days under con- ditions of temperature and stagnation that speedily prove fatal to jarger plants. It seems to be true that, as the young plant grows, it continually requires more and mor? air and a lower temperature, and, at the same time, the chance of its being dislodged seems to in- crease. In midwinter the second or embryonic stage may appear six weeks after germination of the spores. Sporelings germinated late in winter or in the spring from February to May grow much more slowly than those germinated in December, apparently re- quiring several months to reach the embryonic stage. The long and, frequently, branching filaments described above occur mostly in summer and autumn, very few plants apparently developing good POTASH FROM KELP. 7 embryos excepting in midwinter. Observations on the rate of growth of embryonic plants indicate that they may readily attain sufficient size to be visible to the unaided eye within six weeks after appearing as embryos. Thus it may be stated that, under favorable conditions, the pre-embryonic or sexual stage requires six weeks, and the microscopic portion of the embryonic stage requires about six weeks, making a total of about three months from the germina- tion of the spore to the appearance of the visible plant. LATER STAGES. The postembryonic development of the plant has been worked out from observations of plants in kelp beds, on beaches, and on the breakwater at San Pedro. The last place has proved to be of especial service in these investigations, and we wish here to express our appreciation to Dr. N. S. Gardner, of the University of California, _ for suggesting the use of it. Enough young plants were here observed to enable one to piece - out the course of development by comparing them with the young _ plants that came up in the spring. All kelp and other large sea- _ weeds, except such plants of Macrocystis as were reserved for study, were removed from small areas of the rock surfaces of the break- water. Some of the mud with small plant and animal forms was - scraped from the ‘rocks for examination under the microscope. Young plants down to 3 or 4 inches in length were found in very small numbers in November. For three or four months some of these seemed to wear away nearly as fast as they grew, while others dis- appeared. Finally, in February, all the small plants originally se- lected were gone and only three new plants had been discovered. These plants were all about 16 to 18 inches tall. Examination of scrapings collected in November and December revealed small em- bryonic plants resembling Egregia in color rather than Macrocystis. Not until in February was an embryonic plant found that appeared to be Macrocystis. This oecurrence was contemporary with the appearance of embryos in the laboratory culture. At this time young Egregia plants half an inch to over a foot high could be seen in small numbers here and there. Later on, in March, the young Egregia plants were becoming quite abundant, but no new plants of Macrosystis were as yet large enough for identification. All old plants had disappeared over considerable areas. No obser- vations were made in April because of insufficiently low tides. When the breakwater was again visited, early in May, great changes had taken place. In all the crevices, pockets, and other more or less sheltered places among the rocks dense clumps of Egregia plants up to 2 feet high were growing. Plants of Macro- cystis from 1 to 18 inches high could be found among these others. When visited again, the last of May, Macrocystis plants that had measured 10 to 13 inches in height early in the month were 2 or more feet high. All these vigorous young plants were on rocks that were bare in February and still nearly bare in March. From the _ evidence furnished by examination of the rocks, microscopic ex- _ amination of scrapings from the rocks, and experimental cultiva- tion of spores in the laboratory, it seems that young plants of Macro- cystis, some of them 18 inches high, had grown from spores ger- 8 BULLETIN 1191, U. S. DEPARTMENT OF AGRICULTURE. minating not earlier than the previous November and probably not before December or January. Thus a young plant attains a height of 18 inches in the first six months of its life. Very probably under the more favorable conditions of the kelp beds young plants attain a height of from 10 to 15 feet or more in the first six months. The young plants that had measured 18 inches in height in Feb- ruary had changed so much by the early part of May as to be scarcely recognizable. One not far beyond the end of the first sec- tion of the breakwater may be cited as an example. In the middle of February this plant was about 18 inches high, with a slender primary stipe and its first two fronds only well started, a few cysts forming, and the whole plant delicate in appearance. In pre- vious monthly visits, the plant had not been distinguished from the young plants 1 to 6 inches high of the single-bladed kelp, Laminaria farlowtwi, among which it grew. Early in May, less than three months after the plant had been noted as a young plant, with a height of 18 inches, it had a stout primary stipe and main branches, two fronds 5 or 6 feet long—very nearly the length usually attained by plants growing in tide water—with stipes, cysts, and leaf-blades of average size, and 6 additional fronds well started. A considerable number of long, narrow leaves were clustered at the base as in large plants, and on one of these a small sorus was found. When examined under a microscope this sorus was found to have geod spore cases, on both sides of the leaf, containing nearly matured spores. The primary stipe, or “ trunk,” it may be called, had become stout— over one-half inch in diameter—with a flat holdfast at the base, about 4 inches in diameter, hardly large enough to anchor the plant securely. Six additional whorls of stout hapteres or “ roots” were growing out from the stipe above the holdfast. When visited again at the end of the month, the plant had nine good fronds, of which the first two were in the sloughing stage. No fruit was seen, probably because there is a great decline in fruitage in May. All the young hapteres noted the first of the month had grown down and attached themselves to the rock, so that the plant now had a good, stout hold- fast, of the conical or dome-shaped type characteristic of large kelp plants of various species. The primary stipe was now starting out from the underside of one of the larger branches. Working backward from this plant, it may be stated that from the time a young plant has begun to send up its first fronds, not more than four months elapse, if conditions are favorable, until it has produced a clump of fronds of average weight. Then, since plants germinating from the spore in December are sending up their first fronds in May, we can safely say that plants germinating at a time favorable for most rapid development may be producing kelp in commercial quantities in 10 months or less. It is necessary to use the expression, “a time favorable for most rapid development,” because, thus far, only spores germinated in early winter have been found to produce rapidly developing plants. Spores germinat- ing even as early as February, when the water is at its lowest tem- perature, produce sporelings which, while they take on a healthy color, seem to keep their original size for months. Kelp beds torn out by storms in late winter or early spring do not come back until the second season. This discrepancy between — the rate of regeneration of beds destroyed by winter or spring storms ~ POTASH FROM KELP. 7 9 and those dying in the summer is accounted for by the fact that plants from autumn spores develop rapidly, whereas those from late-winter or early-spring spores make little or no progress at first. Thus, in either case, the bulk of the new growth must make its start in autumn or early winter. The San Pedro breakwater has also furnished interesting data regarding phenomena of development of young plants. They start first in crevices or small cavities where they are not exposed to the full wash of the surf. On the more fully exposed surfaces regenera- tion is very slow. The plants that do grow up in exposed situations make a much slower growth than those better protected. Protection from violent wave action has much the same effect on the general appearance of a kelp plant as shading and prctection from wind have on a land plant; that is, the protected plant produces a longer stipe and much larger, and thinner blades than the exposed plant. Plants in exposed places on the breakwater were not more than 1 or 2 inches high when the better protected plants had a height of 16 to 18 inches. Kelps took hold more readily where the rocks were eovered with barnacles and other small animals, and small seaweeds, than where their surfaces were clean. ‘Frequently kelp plants were found attached to small red seaweeds. Where conditions are favor- able, the young plants start thickly, often standing less than an inch apart, the strong ones crowding out the weak as they grow. DEVELOPMENT OF HOLDFAST. Another very important point observed was the rate of develop- ment of the holdfast. The first few whorls of hapteres grow out at very short intervals to form a flat holdfast. This holdfast does not keep pace with the upper parts of a vigorous young plant, and as a result the plant becomes very insecurely anchored. Later on, how- ever, when the primary stipe has become stouter and a number of fronds have been sent up, numerous stout hapteres bud out higher up and securely anchor the plant. REGROWTH. A plant selected for regeneration experiments behaved in a man- ner resembling new plants, as regards seasonal growth. This plant was in a slightly protected place, and was a strong specimen with a somewhat larger holdfast than most of the plants on the break- water had. The fronds were all cut down to a height of 16 to 18 inches in November. Some new fronds were found growing up in December. These began to weather down when 3 or 4 feet long. New fronds appeared from time to time, but wore back too rapidly to produce much foliage during winter. When visited early in May, there were 12 fronds. None of these was more than 7 or 8 feet long. On some fronds, 3 or 4 feet long and growing vigorously, the lower laterals had already formed clusters of four or more leaves each. All fronds found at this time were cut off below the lower- most cyst. By the end of May, 6 new fronds had started, of which the longest had a length of 3 feet. During the seven months that it was under observation, the holdfast of this plant had increased from about 1 foot to 2 feet in diameter, and had died in the center, showing that the plant has a tendency to spread at the base after 56751—23——_2 al fi ~ OO OQ) OOO OO EE EEE EE EEO EO EL al 10 BULLETIN 1191, U. S. DEPARTMENT OF AGRICULTURE. the manner of a clump of mint. This spreading habit of one type of Macrocystis will be referred to later in this bulletin. Many of the basal leaves of this specimen fruited in midwinter, but no fruit was seen in May. YOUNG PLANTS. In addition to the observations at San Pedro, careful watch for young plants was kept in various kelp beds and on several beaches. Plants with only one-or two fronds, and these with rather slender stipes, thin-walled cysts, and rather delicate leaves such as one would naturally expect young plants to have, are rarely seen in kelp beds. No changes take place in the appearance of a kelp bed by which one can recognize the coming in of a new generation. At more or less irregular periods, but chiefly in spring and early summer, young plants come in on the beaches in fairly large num- bers, though not at all comparably to the young Nereocystis plants that come in on northern California beaches in midsummer. In May, 1919, these young plants appeared in greater number on the beach at La Jolla than at any other time or place considered in this bulletin. Many of these could be readily untangled, and were suffi- ciently well preserved for measurement. About 400 of these plants were collected and measured for the purpose of finding the rate of growth. The work was discontinued because many young plants of considerable size were soon found that could not be untangled from the masses of seaweed without breaking, but which would have had to be used in order to get results of real value. During May more than 400 plants were measured, having an average length of 3 feet. These regularly had 2 fronds, 2 narrow leaves between the fronds, a slender primary stipe about 4 inches long, and a flat holdfast about 2 inches wide. ‘The development of the holdfast and the size of other parts indicated that they had grown at four or five times the rate of the plants observed at San Pedro. In addition to these plants, there were others measuring 15 to 20 feet in length. These had their third and fourth fronds well started and the holdfast better developed than in the young plants, but were apparently not more than 7 or 8 months old. On the other hand, very small plants were often found. Some of these were attached to the holdfast of larger young plants, or had grown up so close beside them as to let go and drift ashore with them. Other examples were found of young plants having started on old stems of seaweeds, which had broken off and come ashore with them. One old stipe, apparently Egregia, less than 2 feet long, had more than a dozen young plants attached to it. The smallest plants thus were only 0.2 inch long. These had already formed a stipe, but there appeared to be but little expansion at the base. The blade was very thin and perfectly plane, with a smooth, entire margin. These tiny plants all had the tip more or less worn off. Macrocystis plants can hardly be distinguished from Egregia or other young kelps, especially when they come in with most of their color faded out. Among the drift plants they were regarded as Macrocystis because of having come from too great a depth for shore kelps. On San Pedro breakwater it is not easy to identify Macrocystis before the grooves for the first split begin to appear, because of the great quantity of POTASH FROM KELP. 11 shore kelp of which two species, Laminaria farlowii and Eisenia arborea, also have corrugated leaf blades. Young plants 3 or 4 feet long were found in some number on the beach at La Jolla in November, 1917. One or two small plants were found among these. Again, in February, 1918, a very few small _ plants were found, of which two were undivided. In July, 1918, _ young plants from 1 to 12 feet long came in, in numbers comparable - to the smaller plants found in May, 1919. It would thus seem from these observations that young plants may be found at nearly any time of the year, but in abundance only from late spring to mid- summer. Plants brought in by storms in winter or early spring usually have large fronds and well-developed holdfasts a foot or more in diameter. Of the other plants, the holdfasts are commonly _ dead in the center, some having only a shell of living hapteres around the outside. The center begins to die, apparently, in the second year, so that these plants are more than a year old. Some of the largest may be 5 years old or older. The comparatively smal] number of plants that come in on the beaches certainly indicates a smaller amount of renewal than occurs in a bed of annual kelp. It is not possible, though, to make any near estimate of the age attained. Most plants are probably destroyed by being torn from their anchorage and carried ashore. STAGES OF DEVELOPMENT. The stages in the development of the plant, _ after it has become of sufficient size to be (8s) = . : : Ly seen without the microscope, may be rather hastily sketched, since Skottsberg (5)* has de- scribed them in detail. In the earliest stages ("Ga qakONS Ray Shen thus found, the plant has a single leaf with a 6 priaty See broadly rounded base (fig. 3), a distinct stipe, pnickiry Splits visible at and a conical holdfast. As it grows, hapteres tie aan ee bud out in whorls above the original holdfast. The increase in the length and the diameter of hapteres is very rapid at first. The stipe enlarges upward as successive whorls of hapteres are given off. The intervals between the first few whorls are so short, and the increase in length of successive hapteres so rapid, that the holdfast of a young plant becomes very flat. When a rapidly growing plant has attained a height of 4 or 5 inches, the first longitudinal split begins to develop at the base of the leaf- blade. A vigorous plant may have a height of nearly 2 feet before the right and left halves of the primary blade are fully separated. By the time the first split has attained a length of 1 inch, the secondary splits begin to occur. In contradiction to what Skotts- berg (&) states, the first splitting usually separates a symmetrical blade into equal divisions. The secondary splits separate the first two leaves into unequal parts, of which the outer or marginal two are larger than the inner or central pair. The margins begin to 1 Figures in italics in parentheses refer to literature cited at the end of this bulletin. 12 BULLETIN 1191, U. S. DEPARTMENT OF AGRICULTURE. thicken and lengthen below, giving rise to the two main arms or branches. The outer segments begin to outgrow the inner pair, and very soon the serial splits begin to appear, showing their evolution into the growing tips of the first two ascending fronds. In some plants all the leaves are still attached at their tips to the original blade, even after the first cysts have begun to round up. The char- acteristic marginal teeth do not appear before the plant has attained a height of 5 or 6 inches.