Sacra pregets Oet ea aniad + - ae nt 7 he : pas ree Re al er? ¥ roa —~ ne aa te™ ee rare et ners TNs : ~ Link oo Ne Geis TRE : Z nae ante | Serene im Ee Grate I eno. eee yy we a MS rena rer x 4 ee ‘ ape Se eres i Apart: aehad fate SSuT Ate a eh de IW VEIN OOP Ea Wd 0 SS eR eR ee ee ee ee ~’ sa1uvudly saiuvugiy INSTITUTION saiuvugiq INSTITUTION RARIES SMITHSONIAN INSTITUTION NOILNLILSNI NVINOSHLINS SAIYV ” Zz Ca < i n F = < = TZ < = : 2 Wy i YG = oO a SS w JEKE a w fe) Ze IWS o GY fh ee ee fe) 2 E Ee Aird = fl = = IW =" = = < he ee: a ” = ; _NVINOSHLINS S3I1YVYEI1 LIBRARIES INSTITU : aca 3 g a Ge = 4 an = =i S ) Oo oO S S 2 -RARIES SMITHSONIAN INSTITUTION NOILNLILSNI NVINOSHLINS SJIYV? SaINVUSIT LIBRARIES =< Zz 2 = ; iS) ° a 2S : typ * cs ES : @ 3 : Ba a : y 2) 3RARIES SMITHSONIAN _INSTITUTION NOILALILSNI NVINOSHLIWS = a = ” Ws es GS. Ss ac ct SONS fod <5 q S a WSS = a = co = co E g a 2 ea i SSIYVYGIT LIBRARIES SMITHSONIAN INSTITU a = og = i ig wo o ow & wo 2 = 20 zs ) = s. - = SSS & a = a as SQ = Fe see ASS m a >» = D = n 3RARIES SMITHSONIAN INSTITUTION NOILNLILSNI NVINOSHLINS S31uVi we = a) 2) ; = < = = Uy = = = a Y SA B ws w : SN oO 2 oe oO e a S = = = ae ae rN > = >" = A — 7p) rs ud “as ILALILSNI_ NVINOSHLINS S3tYVYEIT LIBRARIES SMITHSONIAN INSTITU LIBRARIES SMITHSONIAN LIBRARIES NOILNLILSNI NOILALILSNI NOILALILSNI ee be eI See Se eee ee eS Sa1uvual vas INSTITUTION INSTITUTION AS saluvuai SAteye al SRARIES SMITHSONIAN INSTITUTION NOILNIILSNI_NVINOSHLINS S31uvVi . z Ly Zs n z n : = < = = = Wi 4 z \ a z a Y je fo) SY 25 ; O tL Of, Mm ~~ SW n Sap) ep DW SVN oO a A WN (S) ac oO i, y; NS z i \ WS =, = — Le eee: 3 a in ILSNI_NVINOSHLINS | Sa fYvVddi)l LIBRARI ES SMITHSONIAN INSTITU 2 2 2 — = a =, 5a fs : eS : a, oc oe £F = i es o = Se) ay = s 2 s SRARIES SMITHSONIAN INSTITUTION NOILNLILSNI NVINOSHLIWS a a = cs a z Se) S) ea 5 O ma 2, A ie = S \) + = ce hy a = E QS ey ey = = WO ££ E “yyy = = a NX Ss = ee z , ee IINLILSNI NVINOSHLINS SSIYVYE!IT LIBRARIES SMITHSONIAN _ We ES a ae z Zz peer ar a NS = 4s = Oo a DB df 9° LY. “a x | 5 g BYUG 2X” 8 b = = Gy ei V2 = = > ; = ee ox w Pos 79) * 2 Uv”) SRARIES SMITHSONIAN INSTITUTION NOIEOLISNI NVINOSHLINS SJA1IYV cs raz ee & WE W < | = < = RE < o oc SON oc co = mo = . NY m a Z a =. ey ILOLILSNI NVINOSHLINS SS!YVYdIT LIBRARIES SMITHSONIAN _INSTITL a i 2 lia = ; ies bis S = w EN aa w — Ye y w 2 Lg 5 > & Guy, a > cE Wf, fi > 2 WHE 2 = O fi 2 = SS Ww pe a ear = oS re m > m (ep) = wm Ss wn” SMITHSONIAN INSTITUTION NOILOALILSNI NVINOSHLINS S3IYV: z Se aaa ae sj . = hi, = = WE = Xgy | GY? z Se SAS ro) * SING o GPE 2 a NS = MWY 2 GK’ = Zz ’ aN = iy S = = a z SAIYVYSIT LIBRARIES SMITHSONIAN iNSTITU ILALILSNI NVINOSHLIWS \ LIBRARIES SMITHSONIAN 7, G LIBRARIES NOILNLILSNI NOILALILSNI NOILALILSNI any Ib nag it 2 os ah wt i ns “¥ me, a oS ate coe CT BRAR YC UL Se PUBLID HEALTH SERVICE tau ORS 2 ERE ANNUAL ete ibe THE _ BOARD OF REGENTS OF 4 THE SMITHSONIAN INSTITUTION OPERATIONS, EXPENDITURES, AND CONDITION OF THE INSTITUTION FOR THE YEAR ENDING JUNE 30 1934 Oh ahaa AED rn gt Sean. ae ro ND Arr hate a v7 ae i Ne i y Pa ah ay J 8S 2h NAL Tiga SMITHSONIAN INSTITUTION WASHINGTON fTo ‘OV, J, BP ev cise yiag e dD nin uc 5 a) ’ 5 tag U, we PUBLIC ! ALTH SERVICE a ei, tf? ry he 5 HiUEON, u, Ue ANNUAL REPORT BOARD OF REGE OF TEE NTS OF THE SMITHSONIAN INSTITUTION SHOWING THE OPERATIONS, EXPENDITURES, AND CONDENION OF “THE INSTITUTION FOR THE YEAR ENDING JUNE 30 1934 (Publication 3305) UNITED STATES GOVERNMENT PRINTING OFFICE WASHINGTON : 1935 For sale by the Superintendent of Documents, Washington, D. C. Price $1.00 araur « LETTER OF TRANSMITTAL SMITHSONIAN INsrITUTION, Washington, January 28, 1936. To the Congress of the United States: In accordance with section 5593 of the Revised Statutes of the United States, I have the honor, in behalf of the Board of Regents, to submit to Congress the annual report of the operations, expendi- tures, and condition of the Smithsonian Institution for the year ended June 30, 1934. I have the honor to be, Very respectfully, your obedient servant, C. G. Aszor, Secretary. It . a | ve dea : > wad A we | Dita aes ; ; ot ay 1} 7 7 Tad y vite i J] - : | aa ay ‘ne CONTENTS iistiof ofieiniss a twaclws Ue syel. ate: ade pee) vy ed tach sh bye Dag ee etl een Onistandine Events 2tawt tao SF RAE Retin ead inr gar Dery. sel eyt ans Summanyeor cheryear si activivies=s226 ssa s2ou- 2-8 aoe ease oo eee Se MP RerestaplishMenges =e uo cars Oster tee Sanam Ny oe ety mee ae Mine EDOSEOLOLsReP CNUs a see eee eS A ee Eye Lee ee ee DERYTANEE Sa Y=) = == aes = a= 19, 215. 64 Cash income from endowments for specific use other than I'reer endowment and from mis- cellaneous sources (including refund of tempo- TAany AGOVANCCS) eee eS ee ee 50, 821. 08 1 This statement does not include Government appropriations under the administrative charge of the Institution. 74. ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 CASH BALANCES, RECEIPTS AND DISBURSEMENTS DURING THE FISCAL YEAR—continued Receipts—Continued. Cash capital from sale, call of securities, ete. (torbeuweinwested)2Aeee 4 sae ek eee eee $133, 066. Total receipts other than Freer endowment_____---_- Cash receipts from Freer endowment: Income from investments, ete___.------- $200, 355. Cash capital from sale, call of securities, CuC nu (toOMbe TelimviesteC)) == =e nee 5538, 646. Total receipts from Freer endowment___------- ARO GALA. Rees 2 SEU Sa Oe ae See Disbursements: From funds for general work of the Institution: Buildings, care, repairs, and alterations___. $2, 138. DUVAMUAHUIRS oval TIBI live General-admimistration?e2 =) sa= sean oe 21, 655 Taipan yeceees topes, pe Be ap a ar ee 2, 500. Publications (comprising preparation, print- ing. and distribution) eee a ee eee ne 18, 035. Researches and explorations_____.___.----- 23, 001. Specialahmmade eee se 58S ee Nee ae ees aan 1, 400. International exchanges__._._..-..-=ies<< 4, 415. From funds for specific use, other than Freer endowment: Investments made from gifts, from gain from sale, etc., of securities and from SE iva Fs! Oyay mavefoponey_— Se ee 9, 089. Other expenditures, consisting largely of research work, travel, increase and care of special collections, ete., from income of endowment funds and from cash gifts for specific use (including temporary SIGN CES) = a ee eee ee Lek ne eet 68, 711. Reinvestment of cash capital from sale, calltofisecuriticsseieo ee eee ee 104, 596. From Freer endowment: Operating expenses of the gallery, salaries, fieldiexpenses jetes. sae ee ee 51, 890. Purchasesiofaruioblectsas= =e see a 132, 736. Investments made from gain from sale, etc. of securities and from income______-__- 26, 1381. Reinvestment of cash capital from sale, call ofsecurities;,etes- 2 2s eee ee eee 496, 440. 2 This includes salaries of the Secretary and certain others. 11 $275, 470. 93 754, 002. 37 1, 212, 881. 55 73, 165. 51 182, 397. 50 707, 199. 74 250, 118. 80 1, 212, 881. 55 REPORT OF THE EXECUTIVE COMMITTEE 75 EXPENDITURES FOR RESEARCHES IN PURE SCIENCE, EXPLORATIONS, CARE, INCREASE, AND STUDY OF COLLECTIONS, ETC. Expenditures from general funds of the Institution: UDCA LOTS ear ea eel = ee $18, 035. 98 Researches and explorations_____.________-_- 23, 001. 50 SSS $41, 037. 48 Expenditures from funds devoted to specific purposes: Researches and explorations_________-_____-- 39, 737. 54 Care, increase, and study of special collections. 15, 057. 46 Rublications223290 28 Zeke ee eee 2, 023. 93 ————_—-— 56, 818. 93 SUR 3) LSet gk a4 a pe me aa 97, 856. 41 The practice of depositing on time in local trust companies and banks such revenues as may be spared temporarily has been con- tinued during the past year, and interest on these deposits has amounted to $1,106.47. The Institution gratefully acknowledges gifts or bequests from the following: Dr. W. L. Abbott, purchase of collections of certain birds of the Himalayas. Dr. Adolph M. Hanson, further income from certain royalties for conducting scientific work of the Institution. Dr. T. Wayland Vaughan, publication of papers on Foraminifera. Mr. Eldridge R. Johnson, for expenses in connection with deep-sea and other oceanographic explorations. Mrs. Mary Vaux Walcott, for publication of pitcher-plant volume of North American Wild Flowers. Research Corporation, further contributions for researches in radiation. Dr. William Schaus, collection of Lepidoptera. Mr. John A. Roebling, further contributions for researches in radiation. All payments are made by check, signed by the Secretary of the Institution, on the Treasurer of the United States, and all revenues are deposited to the credit of the same account. In many instances deposits are placed in bank for convenience of collection and later are withdrawn in round amounts and deposited in the Treasury. The foregoing report relates only to the private funds of the In- stitution. The following appropriations were made by Congress for the Government bureaus under the administrative charge of the Smith- sonian Institution for the fiscal year 1934. SLATES TATICEONP CORES SE 4 ee SS. a ee eo ee ee $32, 500 iGermaronaL MXCKANBES: =< 2228. 22 Bate ee Se ee 38, 500 AGITETIC ATI eH Gt O10 Gry meena = hes Ned te, ee ee ee oe 50, 000 Astrophysical Observatory National Museum: Maintenance and operation... 9-22. 2225s Sec $128, 500 iIPresenvation. Ofcollecthions== ss) = ae eee eee 509, 000 637, 500 76 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 National Gallery of7Arts: see SoS os ee ee eee ae $29, 500 National’ ZoologicalPark: 6 96. 225-2 os See ee eee ae ee eee 180, 000 Printing.and binding ss eee Ee a eee eee eee 5, 500 oye Neen eee See el ee ee ene Sete oe ST ee en SS See 1, 000, 000 There was also an allotment of $3,000 made by the United States Commission of the Chicago World’s Fair Centennial Celebration for participation by the Smithsonian Institution in ‘‘A Century of Prog- ress’’, and a grant of $7,625 from the Federal Civil Works Admin- istration to cover necessary overhead expenses in connection with the project ‘‘ Archaeological Excavations.” The report of the audit of the Smithsonian private funds is printed below: SEPTEMBER 25, 1934. Executive Commitrer, Boarp oF REGENTS, Smithsonian Institution, Washington, D. C. Sirs: Pursuant to agreement we have audited the accounts of the Smithsonian Institution for the fiscal year ended June 30, 1934, and certify the balance of eash on hand June 30, 1934, to be $252,018.80 [which includes $1,900 held in cash at the Institution]. We have verified the record of receipts and disbursements maintained by the Institution and the agreement of the book balances with the bank balances. We have examined all the securities in the custody of the Institution and in the custody of the banks and found them to agree with the book records. We have compared the stated income of such securities with the receipts of record and found them in agreement therewith. We have examined all vouchers covering disbursements for account of the In- stitution during the fiscal year ended June 30, 1934, together with the authority therefor, and have compared them with the Institution’s record of expenditures and found them to agree. We have examined and verified the accounts of the Institution with each trust fund. We found the books of account and records well and accurately kept and the securities conveniently filed and securely cared for. All information requested by your auditors was promptly and courteously furnished. We certify the balance sheet, in our opinion, correctly presents the financial condition of the Institution as at June 30, 1934. Respectfully submitted. WILLIAM L. YAEGER & Co., WILLIAM L. YAEGER, Certified Public Accountant. Respectfully submitted. Freperic A. DELANo, R. Watton Moors, Joun C. Merriam, Executive Committee. GENERAL APPENDIX TO THE SMITHSONIAN REPORT FOR 1934 77 7 e, tv, ts sia if “eres! Os + we | oy WA ae aa oar | Cainy. ‘nd Y WANs pera oa 2 ti wh : doshe ro so : en ¢ * i uy fe el i ae a bt y ma eve ora Seat ae Re ob Le OA pe! cn Ay BWenk 8) a Gy > Be vege: Wie" . ; 24M alll ue Cs ae Pht vale ne ws ’ : ee , oy : : Y a ara pe ven | Ly nea Rien yh aN 1) Ae as hi eae ei Aayy ye auld a Say a oe, oe nae eka ee ees 7 Par sc yet ote ates : me ae CN ile GORE Mel Bit hi a i int as i aac 9 oo rl aie Sc I ye A el a a en Heke ako ee ‘gti, ‘i ene eae: onieat Vit ise ine al, # Px ans Brae a ha na ies PO Ade > caiaiainele ee din a 4 t a a % a é at i (ie ca = rs i & pus. sy res ‘ on ayia, Mt wie aie $ a ee Oe eee ee il) remeat nes + che 7 — : . vm hr Senaiel oe Pcen Seer 7 moranten nan = “he ious ie in Wi fate s ara re aaa we dealin Bs ited | rh pines ree D - a ae ae ME poe Pe nae opt gyt eosin wis se lane ie aa PTR eRe Se . me oie NC GGT es & Cpe a Red aL ag aie ey ae cots so et ea _ re ; : ; ; _ 4 ¥ Bes nw): 150 th oh Re, 1a Bie eee bay N, ena >. Pl 4 af os. © pay pa) AP Cpe ioe Ae 4. a ee wees im ae \ueheone Tae ame ne Te be 4 Livep = Oe 52 einen { i - 1" => ia : 7 - > s oi Cea 1S 7 ene ADVERTISEMENT The object of the Grnrrat Appenprx to the Annual Report of the Smithsonian Institution is to furnish brief accounts of scientific discovery in particular directions; reports of investigations made by collaborators of the Institution; and memoirs of a general character or on special topics that are of interest or value to the numerous correspondents of the Institution. It has been a prominent object of the Board of Regents of the Smithsonian Institution from a very early date to enrich the annual report required of them by law with memoirs illustrating the more remarkable and important developments in physical and biological discovery, as well as showing the general character of the operations of the Institution; and, during the greater part of its history, this purpose has been carried out largely by the publication of such papers as would possess an interest to all attracted by scientific progress. In 1880, induced in part by the discontinuance of an annual sum- mary of progress which for 30 years previously had been issued by well-known private publishing firms, the secretary had a series of abstracts prepared by competent collaborators, showing concisely the prominent features of recent scientific progress in astronomy, geology, meteorology, physics, chemistry, mineralogy, botany, zool- ogy, and anthropology. This latter plan was continued, though not altogether satisfactorily, down to and including the year 1888. In the report for 1889 a return was made to the earlier method of presenting a miscellaneous selection of papers (some of them origi- nal) embracing a considerable range of scientific investigation and discussion. ‘This method has been continued in the present report for 1934. 79 wl ur uel dat oie "aetna ae bs a (Nitnake An alnwewer Tatt labile et samehieraerel a lov rs nek 14 shan prolate To erwet edu tients Pericnl bgt (ita eoSoe- dail, 4 to etijarsin bua Zhe bre seyante 08 ilar vo Sushi ak ae has sit i o pots a be ails. To we (with ath) to testy Weatatony, na Hak ene al) pris Ob eins yhina ced ae foder® PoUAM tail Hat crioyeuie ie ee all ab asia fata, Lea ge liz iD) abyrougi baal antsogualy Roa is dai teenrigsr Othe, iv -tab ver taict Liteeatins wild, atvnila al ee : SE ae et i Se ete | m0 oder ny yuh Sotolah sce serene IE pe read Lytigtte ae 16! cae tea ty al yi al beinbine 6 ae ak ecomen Cg ask Puen rity taney, Aa) ee raat {a eerie no inal ea ALE apeDb yauieiig pena tsk eefoekairo) igttivh inte mncwdally etteqiing id ihe + atc MenipGerrien 1h Seer Mery siHanins Seweet ta aelder tae 4 od Thus yuntad paiebyrasiint werilelini euieyhy seubliranteas We snl jis goed’ Senco: enw Why. re Oe a Thin Daw ee Saat ted et patholo hea veoh wien yo taedan vlan ih fees Rurdbgeans acalbencr old 07 Abia eae taal Poen, te ORT, tk 7 at, ie HEA be a1aL9 )> Saeyet Yo norte inion ces 3) ne aera aliiigeme Te wget ainiebinmen we iene. (I Meee os xt bouadiass oor axl oda AEE THE NEW WORLD-PICTURE OF MODERN PE Si¢s” By Sir JAMES H. JEANS The British Association assembles for the third time in Aberdeen— under the happiest of auspices. It is good that we are meeting in Scotland, for the Association has a tradition that its Scottish meet- ings are wholly successful. It is good that we are meeting in the sympathetic atmosphere of a university city, surrounded not only by beautiful and venerable buildings, but also by buildings in which scientific knowledge is being industriously and successfully accumu- lated. And it is especially good that Aberdeen is rich not only in scientific buildings but also in scientific associations. Most of us can think of some master mind in his own subject who worked here. My own thoughts, I need hardly say, turn to James Clerk Maxwell. Whatever our subject, there is one man who will be in our thoughts in a very special sense tonight—Sir William Hardy, whom we had hoped to see in the presidential chair this year. It was not to be, and his early death, while still in the fullness of his powers, casts a shadow in the minds of all of us. We all know of his distinguished work in pure science, and his equally valuable achievements in applied science. I will not try to pay tribute to these, since it has been arranged that others, better qualified than myself, shall do so in a special memorial lecture. Perhaps, however, I may be per- mitted to bear testimony to the personal qualities of one whom I was proud to call a friend for a large part of my life, and a colleague for many years. Inside the council room his proposals were always acute, often highly original, and invariably worthy of careful con- sideration; outside, his big personality and wide range of interests made him the most charming and versatile of friends. And now I must turn to the subject on which I have specially undertaken to speak—the new world-picture presented to us by modern physics. It is a full half century since this chair was last occupied by a theoretical physicist in the person of the late Lord Rayleigh. In that interval the main edifice of science has grown 1 Presidential address before the British Association for the Advancement of Science, Aberdeen, 1934. Reprinted by permission from Nature, Sept. 8, 1934. 81 82 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 almost beyond recognition, increasing in extent, dignity, and beauty, as whole armies of laborers have patiently added wing after wing, story upon story, and pinnacle to pinnacle. Yet the theoretical physicist must admit that his own department looks like nothing so much as a building which has been brought down in ruins by a succession of earthquake shocks. The earthquake shocks were, of course, new facts of observation, and the building fell because it was not built on the solid rock of ascertained fact, but on the ever-shifting sands of conjecture and speculation. Indeed it was little more than a museum of models, which had accumulated because the old-fashioned physicist had a passion for trying to liken the ingredients of Nature to familiar objects such as billiard balls, jellies, and spinning tops. While he believed and proclaimed that Nature had existed and gone her way for countless eons before man came to spy on her, he assumed that the latest newcomer on the scene, the mind which could never get outside itself and its own sensations, would find things within its limited experience to explain what had existed from all eternity. It was expecting too much of Nature, as the ruin of our building has shown. She is not so accommodating as this to the lmita- tions of the human mind; her truths can only be made compre- hensible in the form of parables. Yet no parable can remain true throughout its whole range to the facts it is trying to explain. Somewhere or other it must be too wide or too narrow, so that “ the truth, the whole truth, and nothing but the truth” is not to be conveyed by parables. The fundamental mistake of the old-fashioned physicist was that he failed to distin- guish between the half truths of parables and the literal truth. Perhaps his mistake was pardonable, perhaps it was even natural. Modern psychologists make great use of what they describe as “ word- association.” They shoot a word at you, and ask you to reply im- mediately with the first idea it evokes in your uncontrolled mind. If the psychologist says “ wave”, the boy-scout will probably say “flag”, while the sailor may say “sea”, the musician “sound ”, the engineer “ compression ”, and the mathematician “ sine ” or “ cosine”. | Now the crux of the situation is that the number of people who will give this last response is very small. Our remote ancestors did not survive in the struggle for existence by pondering over sines and cosines, but by devising ways of killing other animals without being killed themselves. As a consequence, the brains we have inherited from them take more kindly to the concrete facts of everyday life than to abstract concepts; to particulars rather than to universals. Every child, when first it begins to learn algebra, asks in despair “But what are a, y, and 2?” and is satisfied when, and only when, MODERN PHYSICS—JEANS 83 it has been told that they are numbers of apples or pears or bananas or something such. In the same way, the old-fashioned physicist could not rest content with a, y, and 2, but was always trying to ex- press them in terms of apples or pears or bananas. Yet a simple argument will show that he can never get beyond @, y, and 2. Physical science obtains its knowledge of the external world by a series of exact measurements, or, more precisely, by comparisons of measurements. Typical of its knowledge is the statement that the line Ha in the hydrogen spectrum has a wave length of so many centimeters. This is meaningless until we know what a centimeter is. The moment we are told that it is a certain fraction of the earth’s radius, or of the length of a bar of platinum, or a certain multiple of the wave length of a line in the cadmium spectrum, our knowl- edge becomes real, but at that same moment it also becomes purely numerical. Our minds can only be acquainted with things inside themselves—never with things outside. Thus we can never know the essential nature of anything, such as a centimeter or a wave length, which exists in that mysterious world outside ourselves to which our minds can never penetrate ; but we can know the numerical ratio of two quantities of similar nature, no matter how incompre- hensible they may both be individually. For this reason, our knowledge of the external world must always consist of numbers, and our picture of the universe—the synthesis of our knowledge—must necessarily be mathematical in form. All the concrete details of the picture, the apples and pears and bananas, the ether and atoms and electrons, are mere clothing that we ourselves drape over our mathematical symbols—they do not belong to Nature, but to the parables by which we try to make Nature comprek2nsible. It was, I think, Kronecker who said that in arithmetic God made the integers and man made the rest; in the same spirit, we may add that in physics God made the mathematics and man made the rest. The modern physicist does not use this language, but he accepts its implications, and divides the concepts of physics into observ- ables and unobservables. In brief, the observables embody facts of observation, and so are purely numerical or mathematical in their content ; the unobservables are the pictorial details of the parables. The physicist wants to make his new edifice earthquake proof— immune to the shock of new observations—and so builds only on the solid rock, and with the solid bricks, of ascertained fact. Thus he builds only with observables, and his whole edifice is one of mathematics and mathematical formulae—all else is man-made decoration. 111666—35——7 84 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 For instance, when the undulatory theory had made it clear that light was of the nature of waves, the scientists of the day elaborated this by saying that light consisted of waves in a rigid, homogeneous ether which filled all space. The whole content of ascertained fact in this description is the one word “ wave” in its strictly mathe- matical sense; all the rest is pictorial detail, introduced to help out the inherited limitations of our minds. Then scientists took the pictorial details of the parable literally, and so fell into error. For instance, ight waves travel in space and time jointly, but by filling space and space alone with ether, the parable seemed to make a clear-cut distinction between space and time. It even suggested that they could be separated out in prac- tice—by performing a Michelson-Morley experiment. Yet, as we all know, the experiment when performed only showed that such a separation is impossible; the space and time of the parable are found not to be true to the facts—they are revealed as mere stage scenery. Neither is found to exist in its own right, but only as a way of cutting up something more comprehensive—the space-time continuum. Thus we find that space and time cannot be classified as realities of nature, and the generalized theory of relativity shows that the same is true of their product, the space-time continuum. This can be crumpled and twisted and warped as much as we please without becoming one whit less true to nature—which, of course, can only mean that it is not itself part of nature. In this way space and time, and also their space-time product, fall into their places as mere mental frameworks of our own con- struction. They are, of course, very important frameworks, being nothing less than the frameworks along which our minds receive their whole knowledge of the outer world. This knowledge comes to our minds in the form of messages passed on from our senses; these in turn have received them as impacts or transfers of electro- magnetic momentum or energy. Now Clerk Maxwell showed that electromagnetic activity of all kinds could be depicted perfectly as traveling in space and time—this was the essential content of his electromagnetic theory of light. Thus space and time are of pre- ponderating importance to our minds as the media through which the messages from the outer world enter the “ gateways of know- ledge”, our senses, and in terms of which they are classified. Just as the messages which enter a telephone exchange are classified by the wires along which they arrive, so the messages which strike our senses are classified by their arrival along the space-time framework. Physical science, assuming that each message must have had a starting point, postulated the existence of “ matter” to provide such MODERN PHYSICS—JEANS rey) starting points. But the existence of this matter was a pure hypothe- sis; and matter is in actual fact as unobservable as the ether, New- tonian force, and other unobservables which have vanished from science. Early science not only assumed matter to exist, but further pictured it as existing in space and time. Again this assumption had no adequate justification; for there is clearly no reason why the whole material universe should be restricted to the narrow framework along which messages strike our senses. ‘To illustrate by an analogy, the earthquake waves which damage our houses travel along the surface of the ground, but we have no right to assume that they originate in the surface of the ground; we know, on the contrary, that they originate deep down in the earth’s interior. The Newtonian mechanics, however, having endowed space and time with real objective existences, assumed that the whole universe existed within the limits of space and time. Even more character- istic of it was the doctrine of “mechanistic determinism”, which could be evolved from it by strictly logical processes. This reduced the whole physical universe to a vast machine in which each cog, shaft, and thrust bar could only transmit what it received, and wait for what was to come next. When it was found that the human body consisted of nothing beyond commonplace atoms and molecules, the human race also seemed to be reduced to cogs in the wheel, and in the face of the inexorable movements of the machine, human effort, initiative, and ambition seemed to become meaningless illusions. Our minds were left with no more power or initiative than a sen- sitized cinematograph film; they could only register what was impressed on them from an outer world over which they had no control. Theoretical physics is no longer concerned to study the Newtonian universe which it once believed to exist in its own right in space and time. It merely sets before itself the modest task of reducing to law and order the impressions that the universe makes on our senses. It is not concerned with what hes beyond the gateways of knowledge, but with what enters through the gateways of knowledge. It is con- cerned with appearances rather than reality, so that its task resembles that of the cartographer or mapmaker rather than that of the geologist or mining engineer. Now the cartographer knows that a map may be drawn in many ways, or, as he would himself say, many kinds of projection are available. Each one has its merits, but it is impossible to find all the merits we might reasonably desire combined in one single map. It is reasonable to demand that each bit of territory should look its proper shape on the map; also that each should look its proper relative size. Yet even these very reasonable requirements cannot 86 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 usually be satisfied in a single map; the only exception is when the map is to contain only a small part of the whole surface of the globe. In this case, and this only, all the qualities we want can be combined in a single map, so that we simply ask for a map of the county of Surrey without specifying whether it is to be a Mercator’s or ortho- graphic or conic projection, or whatnot. All this has its exact counterpart in the map-making task of the physicist. The Newtonian mechanics was like the map of Surrey, because it dealt only with a small fraction of the universe. It was concerned with the motions and changes of medium-sized objects— objects comparable in size with the human body—and for these it was able to provide a perfect map which combined in one picture all the qualities we could reasonably demand. But the inconceivably great and the inconceivably small were equally beyond its ken. As soon as science pushed out—to the cosmos as a whole in one direction and to subatomic phenomena in the other—the deficiencies of the New- tonian mechanics became manifest. And no modification of the Newtonian map was able to provide the two qualities which this map had itself encouraged us to expect—a materialism which ex- hibited the universe as constructed of matter lying within the frame- work of space and time, and a determinism which provided an answer to the question “ What is going to happen next? ” When geography cannot combine all the qualities we want in a single map, it provides us with more than one map. Theoretical physics has done the same, providing us with two maps which are commonly known as the particle-picture and the wave-picture. The particle-picture is a materialistic picture which caters for those who wish to see their universe mapped out as matter existing in space and time. The wave-picture is a determinist picture which caters for those who ask the question “ What is going to happen next?” It is perhaps better to speak of these two pictures as the particle-parable and the wave-parable. For this is what they really are, and the nomenclature warns us in advance not to be surprised at inconsistencies and contradictions. Let me remind you, as briefly as possible, how this pair of pictures or parables have come to be in existence side by side. The particle parable, which was first in the field, told us that the material universe consists of particles existing in space and time. It was created by the labors of chemists and experimental physicists, working on the basis provided by the classical physics. Its time of testing came in 1913, when Bohr tried to find out whether the two particles of the hydrogen atom could possibly produce the highly com- plicated spectrum of hydrogen by their motion. He found a type of motion which could produce this spectrum down to its minutest details, MODERN PHYSICS—JEANS 87 but the motion was quite inconsistent with the mechanistic deter- minism of the Newtonian mechanics. The electron did not move continuously through space and time, but jumped, and its jumps were not governed by the laws of mechanics, but to all appearance, as Kin- stein showed more fully 4 years later, by the laws of probability. Of 1,000 identical atoms, 100 might make the jump, while the other 900 would not. Before the jumps occurred, there was nothing to show which atoms were going to jump. Thus the particle picture conspicu- ously failed to provide an answer to the question, “ What will happen next?” Bohr’s concepts were revolutionary, but it was soon found they were not revolutionary enough, for they failed to explain more com- plicated spectra, as well as certain other phenomena. Then Heisenberg showed that the hydrogen spectrum—and, as we now believe, all other spectra as well—could be explained by the mo- tion of something which was rather lke an electron, but did not move in space and time. Its position was not specified by the usual! coordi- nates w, y, 2 of coordinate geometry, but by the mathematical abstrac- tion known as a “ matrix.” His ideas were rather too abstract even for mathematicians, the majority of whom had quite forgotten what matrices were. It seemed likely that Heisenberg had unravelled the secret of the structure of matter, and yet his solution was so far re- moved from the concepts of ordinary life that another parable had to be invented to make it comprehensible. The wave parable serves this purpose; it does not describe the uni- verse as a collection of particles but as a system of waves. The uni- verse is no longer a deluge of shot from a battery of machine guns, but a stormy sea with the sea taken away and only the abstract quality of storminess left—or the grin of the Cheshire cat if we can think of a grin as undulatory. This parable was not devised by Heisenberg, but by de Broglie and Schrodinger. At first they thought their waves merely provided a superior model of an ordinary electron; later it was established that they were a sort of parable to explain Heisen- berg’s pseudoelectron. Now the pseudoelectron of Heisenberg did not claim to account for the spectrum emitted by a single atom of gas, which is something entirely beyond our knowledge or experience, but only that emitted by a whole assembly of similar atoms; it was not a picture of one electron in one atom, but of all the electrons in all the atoms. In the same way the waves of the wave parable do not picture indi- vidual electrons, but a community of electrons—a crowd—as for in- stance the electrons whose motion constitutes a current of electricity. In this particular instance the waves can be represented as traveling through ordinary space. Except for traveling at a different speed, 88 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 they are very like the waves by which Maxwell described the flow of radiation through space, so that matter and radiation are much more like one another in the new physics than they were in the old. In other cases, ordinary time and space do not provide an adequate canvas for the wave picture. The wave picture of two currents of electricity, or even of two electrons moving independently, needs a larger canvas—six dimensions of space and one of time. There can be no logical justification for identifying any particular three of these six dimensions with ordinary space, so that we must regard the wave picture as lying entirely outside space. The whole picture, and the manifold dimensions of space in which it is drawn, become pure men- tal constructs—diagrams and frameworks we make for ourselves to help us understand phenomena. In this way we have the two coexistent pictures—the particle pic- ture for the materialist, and the wave picture for the determinist. When the cartographer has to make two distinct maps to exhibit the geography of, say, North America, he is able to explain why two maps are necessary, and can also tell us the relation between the two—he can show us how to transform one into the other. He will tell us, for instance, that he needs two maps simply because he is restricted to flat surfaces—pieces of paper. Give him a sphere instead and he can show us North America, perfectly and completely, on a single map. The physicist has not yet found anything corresponding to this sphere; when, if ever, he does, the particle picture and the wave pic- ture will be merged into a single new picture. At present some kink in our minds, or perhaps merely some ingrained habit of thought, prevents our understanding the universe as a consistent whole—just as the ingrained habits of thought of a “ flat-earther ” prevent his understanding North America as a consistent whole. Yet, although physics has so far failed to explain why two pictures are necessary, it is, nevertheless, able to explain the relation between the particle pic- ture and the wave picture in perfectly comprehensible terms. The central feature of the particle picture is the atomicity which is found in the structure of matter. But this atomicity is only one expression of a fundamental coarse-grainedness which pervades the whole of nature. It crops up again in the fact that energy can only be transferred by whole quanta. Because of this, the tools with which we study nature are themselves coarse-grained; we have only blunt probes at our disposal, and so can never acquire perfectly precise knowledge of nature. Just as, in astronomy, the grain of our photographic plates prevents our ever fixing the position of a star with absolute precision, so in physics we can never say that an elec- tron is here, at this precise spot, and is moving at just such and such a speed. The best we can do with our blunt probes is to represent MODERN PHYSICS—JEANS 89 the position of the electron by a smear, and its motion by a moving smear which will get more and more blurred as time progresses. Unless we check the growth of our smear by taking new observations, it will end by spreading through the whole of space. Now the waves of an electron or other piece of matter are simply a picture of just such a smear. Where the waves are intense, the smear is black, and conversely. The nature of the smear—whether it consists of printer’s ink, or, as was at one time thought, of elec- tricity—is of no importance; this is mere pictorial detail. All that is essential is the relative blackness of the smear at different places— a ratio of numbers which measures the relative chance of electrons being at different points of space. The relation between the wave picture and the particle picture may be summed up thus: The more stormy the waves at any point in the wave picture the more likely we are to find a particle at that point in the particle picture. Yet if the particles really existed as points and the waves depicted the chances of their existing at dif- ferent points of space—as Maxwell’s law does for the molecules of a gas—then the gas would emit a continuous spectrum instead of the line spectrum that is actually observed. Thus we had better put our statement in the form that the electron is not a point particle, but that if we insist on picturing it as such, then the waves indicate the relative proprieties of picturing it as existing at the different points of space. But propriety relative to what? The answer is—relative to our own knowledge. If we know noth- ing about an electron except that it exists, all places are equally likely for it, so that its waves are uniformly spread through the whole of space. By experiment after experiment we can restrict the extent of its waves, but we can never reduce them to a point or, indeed, below a certain minimum; the coarse-grainedness of our probes prevents that. There is always a finite region of waves left. And the waves which are left depict our knowledge precisely and exactly; we may say that they are waves of knowledge—or, perhaps even better still, waves of imperfections of knowledge—of the posi- tion of the electron. And now we come to the central and most surprising fact of the whole situation. I agree that it is still too early, and the situation is still too obscure, for us fully to assess its importance, but, as I see it, it seems likely to lead to radical changes in our views not only of the universe but even more of ourselves. Let us remember that we are dealing with a system of waves which depicts in a graphic form our knowledge of the constituents of the universe. The central fact is this: The wave parable does not tell us that these waves depict our knowledge of nature, but that they are nature itself. 90 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 If we ask the new physics to specify an electron for us, it does not give us a mathematical specification of an objective electron, but rather retorts with the question: “ How much do you know about the electron in question? ” We state all we know, and then comes the surprising reply, “ That is the electron.” The electron exists only in our minds—what exists beyond, and where, to put the idea of an electron into our minds we do not know. The new physics can provide us with wave-pictures depicting electrons about which we have varying amounts of knowledge, ranging from nothing at all to the maximum we can know with the blunt probes at our command, but the electron which exists apart from our study of it is quite beyond its purview. Let me try and put this in another way. The old physics im- agined it was studying an objective nature which had its own exist- ence independently of the mind which perceived it—which, indeed, had existed from all eternity whether it was perceived or not. It would have gone on imagining this to this day, had the electron observed by the physicists behaved as on this supposition it ought to have done. But it did not so behave, and this led to the birth of the new physics, with its general thesis that the nature we study does not consist so much of something we perceive as of our perceptions; it is not the object of the subject-object relation, but the relation itself. There is, in fact, no clear-cut division between the subject and object; they form an indivisible whole which now becomes nature. This thesis finds its final expression in the wave-parable, which tells us that nature consists of waves and that these are of the general quality of waves of knowledge, or of absence of knowledge, in our own minds. Let me digress to remind you that if ever we are to know the true nature of waves, these waves must consist of something we already have in our own minds. Now knowledge and absence of knowledge satisfy this criterion as few other things could; waves in an ether, for instance, emphatically did not. It may seem strange, and almost too good to be true, that nature should in the last resort consist of something we can really understand; but there is always the simple solution available that the external world is essentially of the same nature as mental ideas. At best this may seem very academic and up in the air—at the worst it may seem stupid and even obvious. I agree that it would be so, were it not for the one outstanding fact that observation supports the wave-picture of the new physics whole-heartedly and without hesitation. Whenever the particle-picture and the wave- picture have come into conflict, observation has discredited the MODERN PHYSICS—JEANS Q] particle-picture and supported the wave-picture—not merely, be it noted, as a picture of our knowledge of nature, but as a picture of uature itself. The particle-parable is useful as a concession to the materialistic habits of thought which have become ingrained in our minds, but it can no longer claim to fit the facts, and, so far as we can at present see, the truth about nature must lie very near to the wave-parable. Let me digress again to remind you of two simple instances of such conflicts and of the verdicts which observation has pronounced upon them. A shower of parallel-moving electrons forms in effect an electric current. Let us shoot such a shower of electrons at a thin film of metal, as your own Prof. G. P. Thomson did. The particle-parable compares it to a shower of hailstones falling on a crowd of umbrellas; we expect the electrons to get through somehow or anyhow and come out on the other side as a disordered mob. But the wave-parable tells us that the shower of electrons is a train of waves. It must retain its wave-formation, not only in passing through the film, but also when it emerges on the other side. And this is what actually happens; it comes out and forms a wave-pattern which can be pre- dicted—completely and perfectly—from its wave-picture before it entered the film. Next let us shoot our shower of electrons against the barrier formed by an adverse electromotive force. If the electrons of the shower have a uniform energy of 10 volts each, let us throw them against an adverse potential difference of a million volts. According to the particle-parable, it is like throwing a handful of shot up into the air; they will all fall back to earth in time—the conservation of energy will see to that. But the wave-parable again sees our shower of electrons as a train of waves—lke a beam of light—and sees the potential barrier as an obstructing layer—like a dirty window pane. The wave-parable tells us that this will check, but not entirely stop, our beam of electrons. It evens shows us how to calculate what fraction will get through. And just this fraction, in actual fact, does get through; a certain number of 10-volt electrons sur- mount the potential barrier of a million volts—as though a few of the shot thrown lightly up from our hands were to surmount the earth’s gravitational field and wander off into space. The phenom- enon appears to be in flat contradiction to the law of conservation of energy, but we must remember that waves of knowledge are not likely to own allegiance to this law. A further problem arises out of this experiment. Of the mil- lions of electrons of the original shower, which particular electrons will get through the obstacle? Is it those who get off the mark 92 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 first, or those with the highest turn of speed, or what? What little extra have thty that the others haven’t got? It seems to be nothing more than pure good luck. We know of no way of increasing the chances of individual electrons; each just takes its turn with the rest. It is a concept with which science has been familiar ever since Rutherford and Soddy gave us the law of spontaneous disintegration of radioactive substances—of a million atoms 10 broke up every year, and no help we could give to a selected 10 would cause fate to select them rather than the 10 of her own choosing. It was the same with Bohr’s model of the atom; Einstein found that without the caprices of fate it was impossible to explain the ordinary spectrum of a hot body; call on fate, and we at once obtained Planck’s formula, which agrees exactly with observation. From the dawn of human history, man has been wont to attribute the results of his own incompetence to the interference of a malign fate. The particle-picture seems to make fate even more powerful and more all-pervading than ever before; she not only has her finger in human affairs, but also in every atom in the universe. The new physics has got rid of mechanistic determinism, but only at the price of getting rid of the uniformity of nature as well! I do not suppose that any serious scientist feels that such a state- ment must be accepted as final; certainly I do not. I think the analogy of the beam of light falling on the dirty windowpane will show us the fallacy of it. Heisenberg’s mathematical equation shows that the energy of a beam of light must always be an integral number of quanta. We have observational evidence of this in the photoelectric effect, in which atoms always suffer damage by whole quanta. Now this is often stated in parable form. The parable tells us that light consists of discrete light-particles, called photons, each carrying a single quantum of energy. A beam of light becomes a shower of photons moving through space lke the bullets from a machinegun; it is easy to see why they necessarily do damage by whole quanta. When a shower of photons falls on a dirty windowpane, some of the photons are captured by the dirt, while the rest escape capture and get through. And again the question arises: How are the lucky photons singled out? The obvious superficial answer is a wave of the hand toward Fortune’s wheel; it is the same answer that Newton gave when he spoke of his “corpuscles of light ” experi- encing alternating fits of transmission and reflection. But we read- ily see that such an answer is superficial. MODERN PHYSICS—JEANS 93 Our balance at the bank always consists of an integral number of pence, but it does not follow that it is a pile of bronze pennies. A child may, however, picture it as so being, and ask his father what determines which particular pennies go to pay the rent. The father may answer “ Mere chance ”—a foolish answer, but no more foolish than the question. Our question as to what determines which photons get through is, I think, of a similar kind, and if Nature seems to answer “ Mere chance,” she is merely answering us according to our folly. A parable which replaces radiation by identifiable pho- tons can find nothing but the finger of fate to separate the sheep from the goats. But the finger of fate, like the photons themselves, is mere pictorial detail. As soon as we abandon our picture of radiation as a shower of photons, there is no chance but complete determinism in its flow. And the same is, I think, true when the particle-photons are replaced by particle-electrons. We know that every electric current must transfer electricity by complete electron-units, but this does not entitle us to replace an electric current by a shower of identifiable electron-particles. Indeed the general principles of quantum-mechanics, which are in full agreement with observation, definitely forbids our doing so. When the red and white balls collide on a billiard table, red may go to the right and white to the left. The collision of two electrons A and B is governed by similar laws of energy and momentum, so that we might expect to be able to say that A goes to the right, and B to the left or vice versa. Actually we must say no such thing, because we have no right to identify the two electrons which emerge from the collision with the two that went in. Its as though A and B had tem- porarily combined into a single drop of electric fluid, which had sub- sequently broken up into two new electrons, C, D. We can only say that after the collision C will go to the right, and D to the left. If we are asked which way A will go, the true answer is that by then A will no longer exist. The superficial answer is that it is a pure toss-up. But the toss-up is not in nature, but in our own minds; it is an even chance whether we choose to identify C with A or with B. Thus the indeterminism of the particle-picture seems to reside in our own minds rather than in nature. In any case this picture is imperfect, since it fails to represent the facts of observation. The wave-picture, which observation confirms in every known experi- ment, exhibits a complete determinism. Again we may begin to feel that the new physics is little better than the old—that it has merely replaced one determinism by another. It has; but there is all the difference in the world between the two determinisms. For in the old physics the perceiving mind was a spectator; in the new it is an actor. Nature no longer forms 94 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 a closed system detached from the perceiving mind; the perceiver and perceived are interacting parts of a single system. The nature depicted by the wave-picture in some way embraces our minds “as well as inanimate matter. Things still change solely as they are compelled, but it no longer seems impossible that part of the compulsion may originate in our own minds. Even the inadequate particle-picture told us something very simi- lar in its own roundabout stammering way. At first it seemed to be telling us of a nature distinct from our minds, which moved as di- rected by throws of the dice, and then it transpired that the dice were thrown by our own minds. Our minds enter into both pictures, although in somewhat different capacities. In the particle-picture the mind merely decides under what conventions the map is to be drawn; in the wave-picture it perceives and observes and draws the map. We should notice, however, that the mind enters both pictures only in its capacity as a receptacle—never as an emitter. The determinism which appears in the new physics is one of waves, and so, in the last resort, of knowledge. Where we are not ourselves concerned, we can say that event follows event; where we are concerned, only that knowledge follows knowledge. And even this knowledge is one only of probabilities and not of certainties; it is at best a smeared picture of the clear-cut reality which we believe to lie beneath. And just because of this, it is impossible to decide whether the determinism of the wave-picture originates in the underlying reality or not—can our minds change what is happening in reality, or can they only make it look different to us by changing our angle of vision? We do not know, and as I do not see how we can ever find out, my own opinion is that the problem of free-will will continue to provide material for fruitless discussion until the end of eternity. The contribution of the new physics to this problem is not that it has given a decision on a long-debated question, but that it has re- opened a door which the old physics had seemed to slam and bolt. We have an intuitive belief that we can choose our lunch from the menu or abstain from housebreaking or murder; and that by our own volition we can develop our freedom to choose. We may, of _course be wrong. The old physics seemed to tell us that we were, and that our imagined freedom was all an illusion; the new physics tells us it may not be. _ The old physics showed us a universe which looked more like a prison than a dwelling place. The new physics shows a building which is certainly more spacious, although its interior doors maybe _either open or locked—we cannot say. But we begin to suspect, it May give us room for such freedom as we have always believed we possessed ; it seems possible at least that in it we can mold events = MODERN PHYSICS—JEANS 95 to our desire, and live lives of emotion, intellect, and endeavor. It looks as though it might form a suitable dwelling place for man, and not a mere shelter for brutes. The new physics obviously carries many philosophical implica- tions, but these are not easy to describe in words. They cannot be summed up in the crisp, snappy sentences beloved of scientific journalism, such as that materialism is dead, or that matter is no more. The situation is rather that both materialism and matter need to be redefined in the light of our new knowledge. When this has been done, the materialist must decide for himself whether the only kind of materialism which science now permits can be suitably labeled materialism, and whether what remains of matter should be labeled as matter or as something else; it is mainly a question of terminology. What remains is in any case very different from the full-blooded matter and the forbidding materialism of the Victorian scientist. His objective and material universe is proved to consist of little more than constructs of our own minds. To this extent, then, modern physics has moved in the direction of philosophic idealism. Mind and matter, if not proved to be of similar nature, are at least found to be ingredients of one single system. There is no longer room for the kind of dualism which has haunted philosophy since the days of Descartes. This brings us at once face to face with the fundamental difficulty which confronts every form of philosophical idealism. If the nature we study consists so largely of our own mental constructs, why do our many minds all construct one and the same nature? Why, in brief, do we all see the same sun, moon, and stars? I would suggest that physics itself may provide a possible although very conjectural clue. The old particle-picture which lay within the limits of space and time, broke matter up into a crowd of distinct particles, and radiation into a shower of distinct photons. The newer and more accurate wave-picture, which transcends the frame- work of space and time, recombines the photons into a single beam of light, and the shower of parallel-moving electrons into a continuous electric current. Atomicity and division into individual existences are fundamental in the restricted space-time picture, but disappear in the wider, and as far as we know, more truthful, picture which transcends space and time. In this, atomicity is replaced by what General Smuts would describe as “holism ”—the photons are no longer distinct individuals each going its own way, but members of a single organization or whole—a beam of light. The same is true, mutatis mutandis, of the electrons of a parallel-moving shower. The biologists are beginning to tell us, although not very unanimously, 96 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 that the same may be true of the cells of our bodies. And is it not conceivable that what is true of the objects perceived may be true also of the perceiving minds? When we view ourselves in space and time we are quite obviously distinct individuals; when we pass beyond space and time we may perhaps form ingredients of a con- tinuous stream of life. It is only a step from this to a solution of the problem which would have commended itself to many philoso- phers, from Plato to Berkeley, and is, I think, directly in line with the new world-picture of modern physics. I have left but little time to discuss affairs of a more concrete nature. We meet in a year which has to some extent seen science arraigned before the bar of public opinion; there are many who attribute most of our present national woes— including unemploy- ment in industry and the danger of war—to the recent rapid advance in scientific knowledge. Even if their most lurid suspicions were justified, it is not clear what we could do. For it is obvious that the country which called a halt to scientific progress would soon fall behind in every other respect as well—in its industry, in its economic position, in its naval and military defenses, and not least important, in its culture. Those who sigh for an Arcadia in which all machinery would be scrapped and all invention proclaimed a crime, as it was in Erewhon, forget that the Erewhonians had neither to compete with highly organized scientific competitors for the trade of the world nor to protect themselves against possible bomb-dropping, blockade, or invasion. But can we admit that the suspicions of our critics are justified ? If science has made the attack more deadly in war, it has also made the defense more efficient; in the long run it shows no partiality in the age-long race between weapons of attack and defense. This being so, it would, I think, be hard to maintain in cold blood that its activities are likely to make wars either more frequent or more pro- longed. It is at least arguable that the more deadly a war is likely to be, the less hkely it is to occur. Still it may occur. We canot ignore the tragic fact that, as our President of 2 years ago told us, science has given man control over Nature before he has gained control over himself. The tragedy does not le in man’s scientific control over Nature but in his absence of moral control over himself. This is only one chapter of a long story—human nature changes very slowly, and so forever lags behind human knowledge, which accumulates very rapidly. The plays of Aeschylus and Sophocles still thrill us with their vital human interest, but the scientific writings of Aristarchus and Ptole- my are dead—mere historical curiosities which leave us cold. Sci- entific knowledge is transmitted from one generation to another, MODERN PHYSICS—JEANS 97 while acquired characteristics are not. Thus, in respect of knowl- edge, each generation stands on the shoulders of its predecessor, but in respect of human nature, both stand on the same ground. These are hard facts which we cannot hope to alter, and which— we may as well admit—may wreck civilization. If there is an avenue of escape, 1t does not, as I see it, lie in the direction of less science, but of more science—psychology, which holds out hopes that, for the first time in his long history, man may be enabled to obey the command “ Know thyself”; to which I for one, would like to see adjoined a morality and, if possible, even a religion, consistent with our new psychological knowledge and the established facts of science; scientific and constructive measures of eugenics and birth control; scientific research in agriculture and industry, sufficient at least to defeat the gloomy prophecies of Malthus and enable ever larger populations to live in comfort and contentment on the same limited area of land. In such ways we may hope to re- strain the pressure of population and the urge for expansion which, to my mind, are far more likely to drive the people of a nation to war than the knowledge that they—and also the enemies they will have to fight—are armed with the deadliest weapons which science can devise. This last brings us to the thorny problem of economic depression and unemployment. No doubt a large part of this results from the war, national rivalries, tariff barriers, and various causes which have nothing to do with science, but a residue must be traced to scientific research; this produces labor-saving devices which in times of depression are only too likely to be welcomed as wage-saving devices and to put men out of work. The scientific Robot in Punch’s cartoon boasted that he could do the work of 100 men, but gave no answer to the question—* Who will find work for the displaced 99?” He might, I think, have answered— The pure scientist in part, at least.” For scientific research has two products of industrial importance—the labor-saving inventions which dis- place labor, and the more fundamental discoveries which originate as pure science, but may ultimately lead to new trades and new popular demands providing employment for vast armies of labor. Both are rich gifts from science to the community. The labor- saving devices lead to emancipation from soul-destroying toil and routine work to greater leisure and better opportunities for its enjoy- ment. The new inventions add to the comfort and pleasure, heaith and wealth of the community. If a perfect balance could be main- tained between the two, there would be employment for all, with a continual increase in the comfort and dignity of life. But, as I see it, troubles are bound to arise if the balance is not maintained, and a steady flow of labor-saving devices with no accompanying 98 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 steady flow of new industries to absorb the labor they displace, cannot but lead to unemployment and chaos in the field of labor. At present we have a want of balance resulting in unemployment, so that our great need at the moment is for industry-making discov- eries. Let us remember Faraday’s electromagnetic induction, Max- well’s Hertzian waves, and the Otto cycle—each of which has provided employment for millions of men. And, although it is an old story, let us also remember that the economic value of the work of one scientist alone, Edison, has been estimated at three thousand million pounds. Unhappily, no amount of planning can arrange a perfect balance. For as the wind bloweth where it listeth, so no one can control the direction in which science will advance; the investigator in pure science does not know himself whether his researches will result in a mere labor-saving device or a new industry. He only knows that if all science were throttled down, neither would result; the community would become crystallized in its present state, with nothing to do but watch its population increase, and shiver as it waited for the famine, pestilence, or war which must inevitably come to restore the balance between food and mouths, land and population. Is it not better to press on in our efforts to secure more wealth and leisure and dignity of life for our own and future generations, even though we risk a glorious failure, rather than accept inglorious failure by perpetuating our present conditions, in which these advantages are the exception rather than the rule? Shall we not risk the fate of that over-ambitious scientist Icarus, rather than resign ourselves without an effort to the fate which has befallen the bees and ants? Such are the questions I would put to those who maintain that science is harmful to the race. THE MARKINGS AND ROTATION OF MERCURY’ By E. M. ANTONIADI It is a well-known fact that the planet Mercury has been singularly neglected by astronomers, so that the greatest confusion is reigning as to the reality and configuration of its spots, the duration of its rotation period, or even the existence of its atmosphere. This un- certainty strikes its roots in the smallness of the disk of Mercury; in the practical hopelessness of detecting well-defined markings on his surface at the very low altitude, and consequent rippling air, of twilight and dawn; and in the difficulty of finding the planet itself without an equatorial mounting, at daytime, high above the horizon, and in the overpowering glare of the Sun. In the beginning of the nineteenth century, Schroter drew moun- tains, a dark streak, and other spots on Mercury, from which Bessel deduced a rotation period of 24" 0™ 53° round an axis inclined some 70° to the plane of the orbit. But these objects were illusive. Yet Schroter had called attention to two features which were subsequently confirmed: (1) that the phase was always smaller than it ought to be theoretically; and (2) that the S. cusp looked very often blunted. This last phenomenon was well explained by Schiaparelli as due to the presence of some dusky area near the S. pole, although he did not draw any such marking on his map of the planet. At about the same time as Schroéter, Herschel could detect no spots on Mercury. Prince, in 1867, Birmingham, in 1870, called attention to their observation of white areas, while Vogel seemed to recognize other markings. In 1879 Flammarion saw no spots; and from 1876 to 1881 Trouvelot could only catch a glimpse of a white area at the N. cusp of the crescent phase. In 1882 De Ball drew a curved dusky shading on the morning phase, which Schiaparelli later identified with one of the markings seen by himself; and, in the same year, the eminent English observer, Denning, saw several spots, which I was enabled to confirm in 1927, and from which he concluded that the rotation period was about 25%. Between 1881 and 1889 Mercury was scrutinized in broad daylight by Schiaparelli with his customary perseverance and with the start- 1 Reprinted by permission, with a few additions by the writer, from The Journal of the Royal Astronomical Society of Canada, vol. 27, no. 10, December 1933. 111666—35. 8 99 100 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 ling result that the period of rotation was found to be equal to the period of revolution, the planet completing a rotation of 874.969256 round an axis almost perpendicular to the orbital plane. It is generally stated that Lowell did confirm the conclusions of Schiaparelli. Yet in his 1896-97 map he does not show a single marking observed at Milan, or elsewhere, but only an enormous number of illusive blackish, linear canals, some perpendicular, others parallel, others inclined to the plane of the orbit of the planet. On August 31, 1900, Barnard, using the 40-inch at Yerkes, de- tected in broad daylight “3 or 4 large darkish spots, very much resembling those seen on the Moon with the naked eye,” adding that “one of these dark markings south preceding the center of Mercury was specially noticeable.” In 1907 and the years following, Jarry-Desloges and Fournier drew some dusky spots of Schiaparelli’s chart, which Sormano believed to have been probably confirmatory of the long rotation period, Five years later, Danjon, using a 71-inch refractor in Paris, de- picted admirably some real dark markings on the evening phase, confirming Schiaparelli, and thus succeeding with a modest instru- ment located in the smoke and dust of the great city there, where Lowell had failed with a powerful telescope in the elevated and so highly vaunted tablelands of Arizona. The conclusions of Schiaparelli met a cool reception. Yet a hand- ful of astronomers, among them C. A. Young, KE. W. Maunder, and A. C. D. Crommelin, entertained but little doubt as to the accuracy of the results of the Italian, while the majority of scientists opposed to them a sturdy skepticism. It was thus only 4 years ago that Graff wrote that almost nobody now believed in the 88-day rotation period of Schiaparelli, controverted, as he thought, by the radio- metric measures executed on the small disk of the planet. I never accepted the deductions drawn from the interesting indications of the thermocouple on the planets; and, in the case of Mercury at least, my distrust was proved to be founded by the unexceptionable evidence of observation. Prudence naturally prompted me to have no opinion on the rota- tion period of that planet since I had not studied it telescopically ; but, convinced that the powerful refractor of 33 inches aperture at Meudon could easily help to solve the mystery, I asked my director, M. Deslandres, for permission to use that instrument occasionally on Mercury in daytime—a demand which was favorably received by that most distinguished astronomer, and for which I wish to express here my feelings of deep gratitude. MARKINGS OF MERCURY—ANTONIADI 101 The planet was thus followed near the meridian during the summer months of 1927, 1928, and 1929; and it was soon obvious that its markings, which were often seen quite distinctly, appeared fixed with regard to the terminator for hours together on the same day. Yet they showed, day after day, a pronounced movement of libration in ce Larenienree | ES WZ Ficgurn 1.—Chart of Mercury. Embodying all the markings observed on the planet with the 33-inch Refractor at Meudon, in 1927, 1928, and 1929. By E. M. Antoniadi. The central point, Z, is supposed to have the Sun at the zenith when the planet is in perihelion or aphelion; but as the projection is not an orthographic one, the chart does not give the approximate appearance of Mercury in superior conjunction with the Sun. The letter S. stands for the initial of the Latin word Solitudo, wilderness; and the abbreviation Prom. stands for promontorium. Argyritis is a bright white region, and was discovered in 1882 by the English astron- omer, W. F. Denning. longitude, such as would be necessitated by a uniform rotation of Mercury in a period equal to that of the revolution round the Sun. The axis was found almost perpendicular to the plane of the orbit, its inclination not reaching 7°. Here, then, we had a complete vindication of the conclusions of Schiaparelli.? 2I must state that a very close scrutiny of Venus near the meridian for many months in 1928 with the large telescope has convinced me that Schiaparelli’s period of 2254 102 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 My results are embodied in the figure accompanying this paper. A closer scrutiny with the large telescope, and with better definition under a high Sun, would have revealed a much more detailed struc- ture; but the present map gives a satisfactory view of the most important markings seen by me with certainty on that desolate world. The color of Mercury looked at daytime in the 33-inch almost com- parable with that of the Moon in twilight. The planet appeared yellowish with a slight roseate tinge on the azure of the sky; while a distinct neutral-gray hue was characteristic of its dusky areas.® With the view of avoiding the use of periphrases in the description of the spots, I have given names to the latter, generally drawn from the Greco-Egyptian mythology of the god Mercury. A few names were inspired by the desert state and tremendous heat prevailing on the planet; and I deemed it a duty to christen a bright area by the name of the antique Ziguria, in pious remembrance of Schiaparelli, born at Savigliano, for his truly wonderful discovery of the chief spots and slow rotation of Mercury with a small telescope. The dusky markings of the planet appear larger in the 33-inch than in the telescopes of the Italian astronomer—a fact due to dimin- ished diffraction in the big glass, and one, too, which yields a precious independent proof of the reality of the markings in question. The largest of the gray spots was named “ Solitudo Herme Tris- megisti ”, or “ Wilderness of Mercury the Thrice Greatest ”—a fabu- lous personage, believed by the Greeks and the Egyptians to have invented all sciences, including astronomy. This marking was dis- covered, among others, by me at Meudon; it had not been seen previously on account of its faintness, and I have shown that medium-sized instruments do not reveal pale half-tones on the planets.* The dark area named Solitudo Atlantis, to the right of my map, is certainly much larger now than when it was first drawn 53 years ago. Yet the reality of this apparent change must be considered with the utmost diffidence, as vegetation seems impossible on a world where the temperature rises at least 200—- above the zero of the Centigrade scale. rests on no decisive spots, but on an effect of contrast. The faint markings seen by me on Venus were manifestly atmospheric and variable from 1 day to the other. A calculation of the solar tides on Venus has shown me that her rotation was slackened only twice as much as that of the Earth. Should the absence of a satellite constitute an indication of a slow original rotation (which is doubtful), then the neighbor planet may have a rotation period extending over months, which seems to agree with my observations. In fact, definite spots appeared fixed here several times during more than 3 hours. 3 Schiaparelli found that these spots had a pale brown tinge. This I could not confirm, in spite of the great superiority of the large instrument in showing color. Mars, Jupiter, and Saturn display wonderful hues in it; but the dark spots of Mercury always appeared to me quite as colorless as the Maria of the Moon. «Mars Report for 1909, in Mem. British Astron. Assoc., vol. 20, p. 30. MARKINGS OF MERCURY—ANTONIADI 103 An analysis of past observations has shown me that all the most important spots drawn by De Ball, Denning, Schiaparelli, Jarry- Desloges, Fournier, and Danjon are confirmed by my own observa- tions; and that the principal markings of my map have been partly confirmed with the 33-inch by Messrs. Ritchey, Lyot, Burson, Baldet, Grenat, Roger, Mlle. Roumens, and by M. Swings, of the University of Liége, in Belgium, observing with me Mercury in the large instrument. We thus have the converging evidence of many hundreds of mutual, independent, confirmations of the existence of definite spots on Mer- cury by several well-trained observers, and this always, without excep- tion, in the positions necessitated by a period of uniform rotation equal to the period of revolution. Hence the 88* rotation of the planet is now demonstrated to be established on an immovable basis. The idea of a rapid rotation, of some 24°, rests merely on analogy with the kindred rotation of Mars and of the Earth; and, apart from the decisive conflicting evidence of observation, it has the further disadvantage of ignoring the important action of the bodily tides. Now, I have shown that Mercury is with reference to the Sun in a po- sition comparable with that of Iapetus with regard to Saturn;® and we know, since the days of Cassini, that Iapetus, apart from his libra- tions, presents always the same face to Saturn. The mean distance of [apetus to his primary is 62 mean radii of Saturn; and the mean distance of Mercury to the Sun is 83 solar radii. But the density of the Sun is double that of Saturn; and, applying the sixth power law, which governs the frictional force slowing down rotation, we find that Mercury, as above stated, is with the reference to the Sun in a comparable position with that of Iapetus to Saturn. The duration of such tidal actions comes here into play, and somebody may ask if the Sun is as old as Saturn. A cosmogonist, skilled in the arts of grasping the exact manner in which the various globes of the universe were begotten, can alone clear up that mysterious question. The application of the sixth power law to the satellites has further enabled me to demonstrate that all those bodies known up to 1893 show, apart from their librations, always the same face to their pri- maries.© The problem had to be set in a very particular way, to which I was led by observation; and that is the reason why the law govern- ing the rotation of the satellites had eluded the penetration of such profound mathematicians as Henri Poincaré and Sir George Darwin. The same law will enable us to understand the very reason of the fundamental difference existing between the rotation of the planets and that of the principal satellites; expressing distances in radii of * Letter to Mrs. Maunder, Jour. British Astron. Assoc., vol. 39, p. 86, 1928. * Bull. Soc. Astron. France, vol. 43, pp. 385-398, 1929. 104 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 the primaries, we find that the satellites had their rotation annulled because they were too near their planets; whereas the planets, except- ing Mercury, have preserved the independence of their rotation because they were far too distant from the Sun. Another interesting question is raised by the existence of an atmos- phere around Mercury. That gaseous envelop, like the one surround- ing Mars, is absolutely invisible; but the frequent presence of cloudy veils over the markings of the superficies constitutes a solid proof of its existence. The clouds of the planet were discovered by the acute- ness of Schiaparelli, who found that they often appear as white streaks on the limb, and that they also veil the dark areas, being curiously more frequent on the evening than on the morning phase. The Italian astronomer compared these veils to the clouds of the Earth—a natural, though at present impossible, assumption, as will soon be seen. Yet, excepting this comparison, my independent re- sults have entirely confirmed the statements of Schiaparelli on this question of the atmospheric veils of Mercury. The limb of the planet often showed to me temporary, irregular, whitish arcs of cloud, stretching sometimes over 3,000 miles in length. Toward the central regions, these veils tended to become invisible, their presence being indirectly revealed by the temporary pallor, or invisibility, of the subjacent markings of the surface. It was rarely that a spot be- longing to the superficies would preserve its intensity unimpaired for many successive days; and the veils in question presented all the degrees of condensation, frorn the greatest rarefaction up to an opac- ity which completely obliterated dark areas of the soil measuring more than 2,000 miles across. The changes were sometimes so rapid, that a spot of the length just mentioned, visible with its real intensity through a clear Mercurian air one day, would be utterly invisible 24" later, and conversely. Very often the dark areas had their in- tensity locally diminished for weeks, with an alternate succession of various degrees of pallor, extinction, and final return to their nor- mal appearance. In the course of my inquiry, the hooked dark spot to the right of my chart, named “ Solitudo Criophori”’, was much more often rendered invisible by local veils than any other marking. The clouds of Mercury are much more frequent and more obliterat- ing than those of Mars, whose nature is, however, quite a different one. It is certain that these veils cannot be composed of droplets of water or of particles of ice, like our own clouds. The enormous heat radiated from the Sun renders the existence of water in the liquid state on the sun-lit hemisphere of Mercury impossible, while the deductions of Johnstone Stoney from the kinetic theory of gases make the presence even of aqueous vapour extremely doubtful in MARKINGS OF MERCURY—ANTONIADI 105 the atmosphere of that world. Meantime the low albedo of these clouds, which does not exceed 0.2, is quite different from that of our cumuli at 0.7, so that the only admissible explanation of the atmos- pheric veils of Mercury is that they are probably due to minute particles of dust, raised by the violence of the winds above the gloom of the dark, scorched, and desolate surface. It has been shown by the variation of light with phase that Mer- cury must have a very rough and uneven soil; and his low albedo seems to indicate the presence, on his superficies, of eruptive rocks, of basalt and dark lava. The varying distance from the Sun must tend slowly to disintegrate the rocks exposed to his heat, and this process of destruction must be particularly active along the border- land of the terminator, where the wilderness is exposed to awful variations of temperature, ranging, indeed, over hundreds of degrees Centigrade. “Mercury ”, says Dr. Crommelin, “is probably a parched desert, with nothing to mitigate the intense glare of the Sun on its day side, seven times as fierce as we receive on Earth.”* Professor Ait- ken rightly considers that “ the little planet is not fitted to be the abode of life” *—a conclusion to which the late lamented E. W. Maunder had independently arrived when he wrote that “ the con- ditions of Mercury are so unfavorable for life, that, even if this remarkable relation of rotation period to revolution did not hold good, it would still be impossible to regard it as a world for habi- tation.” ° ™The Star World, pp. 82-83. § Journ. Roy. Astron, Soc. Canada, October 1911. * Are the Planets inhabited?, pp. 116-117. gidaeleere henge nee fhe ae pa ai ae a fi ae For donate; salto ud haaien, ao | ; : Rinioirialk fp one wS ini onol Ena ibadtinie, rubs Armee) sae * if i eliatlly, Rib ROL Henin. 7 lies texan eves snl pradidanean eis | food wilde ta esiollaxpie wih ie pated ead elmnlbatiad atom Yabba tetas ior owt wolrin ed Reg th sada le bere pena ae aio} boeonaa oxwes, esl) atvergatundath cox karte dee Kuvele wiiies phaluoomadas! Ban rotosuneh onesdogna @ yaogya el qeouteblie, elowadw elanmeh adi decal 7 on ade Cove boabist Rahest ou ewquie) weaon sing & walls we. bike eC we or, 4 Pe te eben: drmalesbrtoaee, Bi; ahd oe ai sribiegeenier AL en alee no ase odi..to LS sorter oct shea fax ate § di See. 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Sraae [With 2 plates] The first three-quarters of last century were years of tremendous activity in polar and especially Arctic exploration. Led by such men as McLintock, Franklin, Ross, Barrow, and many others, expedition followed expedition for a long series of years. Naturally, a great deal of novel and extremely interesting observational material was gathered in the course of these expeditions, but, on the whole, and very largely because of the sporadic and uncoordinated nature of the activities, the truly scientific results accruing from so much splendid effort and so great expense were considered meager. Hence it came about that, around 1875, a proposal was put forward by Count Weyprecht, of Austria, for the arranging of a number of simultaneous expeditions which would cooperate on a uniform plan over a full year. The result was the organization of what has come to be known as the First International Polar Year, 1882-83, when 14 expeditions were in the field, 12 to high northern latitudes and 2 to the Antarctic. Great Britain collaborated with Canada in establish- ing a station at Fort Rae, a trading outpost of the Hudson’s Bay Co. on the North Arm of the Great Slave Lake. From that expedition Captain Dawson, R. E. (who in 1932 died as Colonel Dawson), with his party of engineers trained as observers and with the assistance of Canadian canoe men and guides, brought back results whose value and usefulness have not been fully explored to this day. During that First Polar Year all the stations were fully equipped with such instru- ments as were then available for a comprehensive series of observa- tions in meteorology and terrestrial magnetism; they worked on a common prearranged plan. Practically and scientifically, from the point of view of the interna- tional collaboration as well as Britain’s share in it, the year’s activi- ties were completely successful. 1The G. J. Symons’ Memorial Lecture delivered on Mar. 21, 1934. Reprinted by Permission from the Quarterly Journal of the Royal Meteorological Society, vol. 60, no. 256, July 1934, 107 108 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 Since 1882 progress in meteorology and cognate lines of geophysi- cal investigation—though probably less spectacular than in some of the other domains of physical science—has been very great. A vast number of new problems have arisen; the fields of inquiry and ob- servation have grown ever wider—and higher. In 1882-83 none of the expeditions, so far as I know, carried out any upper air work. Their efforts were necessarily confined to surface meteorology. In terrestrial magnetism hourly readings by eye of instruments designed to give the three major elements in the earth’s magnetic field were as much as the expeditionary technique of those days allowed. And the description of the state of the sky at each hour covered the demands of the time in auroral observations. In recent years, however, meteorologists have been requiring more observations over an increasingly wide area and more detailed data on the characteristics and circulation of the atmosphere up into and beyond the stratosphere. Again, the study of states of disturbance and quiet in the earth’s magnetic field has shown that one observatory can no longer be considered representative of a large area of the earth around it; the changes in the magnetic field are fine structured in space as well as in time, so that a close network of magnetic stations equipped with continuously recording instruments is now needed. And for observations in aurora to serve their best purpose in linking up with the associated magnetic disturbance on the one hand and the variations in height and intensity of ionization in the several con- ducting layers of the high atmosphere on the other, precise determi- nations of the position of the aurora in space are required from as many and as widely distributed localities on the earth’s surface as possible. Thus we see that from all angles of meteorology, terrestrial mag- netism and auroral investigation, a fresh Polar Year program was urgently required on a much more intensified and extensive basis than that of 1882-83. The suggestion, put forward by Admiral Dominik of the Deutsche Seewarte, Hamburg, to hold the repetition in 1932-33—the jubilee year of the First Polar Year—was therefore generally welcomed. An International Commission representative of the meteorological services of many countries was set up to organize the project on a world-wide basis, and national committees were convened to carry out the general recommendations in each separate country. In Britain the national committee had representatives from the Royal Soci- eties of London and Edinburgh and six other interested institu- tions, including the Royal Meteorological and Royal Geographical Societies. Col. Sir Henry Lyons became its chairman and Dr. Simp- son its secretary. Despite the grave financial stringencies of the times, funds to the extent of £10,000 were put at the disposal of the POLAR YEAR EXPEDITION—STAGG 109 committee by the Government through the Air Ministry, and large and generous donations were made in instrumental and foodstuff equipment by upwards of 50 manufacturing and wholesale firms. For obvious reasons, it had been one of the guiding principles of the international program that, as far as possible, the stations oc- cupied 50 years ago should be reestablished, with, of course, as many additional ones as possible to complete the circumpolar network. And, further, though it was true that special efforts were to be made in high latitudes, where systematic observational material is at once most scanty and most important, the program of meteorological, auroral, and magnetic work was to be intensified throughout the world. It reflects great credit on the efforts of the International Polar Year Commission and especially on its most enthusiastic and energetic president, Dr. la Cour, director of the Danish Meteorological Serv- ice, that in spite of the incidence of the world-wide financial crises just at the time when preparations were in progress, some 46 differ- ent countries have taken part in the Polar Year activities, 23 of which have been able to set up special stations either in their own territory or that of other countries more suitable for the work. A map showing the distribution of Polar Year stations is reproduced in figure 1. To this general program Britain’s contribution has been fourfold: (1) By collaboration with her permanent and regular meteoro- logical stations and observatories, including ships at sea. (2) By organizing a scheme of special auroral observations in Scotland and the northern islands—a work largely in the hands of the Royal Society, Edinburgh. (3) By subsidizing a party under Prof. E. V. Appleton for mak- ing an extensive, novel, and very valuable series of observations of conditions in the ionosphere over Tromso. (4) By reoccupying the station at Fort Rae, established 50 years ago. In the party of 6 selected by the National Committee for the work in Canada, 4 of us, Messrs. Morgans, Sheppard, Grinsted, and I, were from the Meteorological Office staff; the fifth, Mr. A. Stephenson, from the geography department, Cambridge, had had experience of Arctic work with the British Arctic Air Route Expedition to Greenland in 1980-31; and Mr. Kennedy, our sixth member, acted as our steward-mechanic. All six of us were very thoroughly examined by the Air Ministry medical staff before being accepted, since our station would be far from skilled medical aid for at least 14 months and our personnel was too small to include a doctor. Mr. Grinsted and Mr. Stephenson had, however, undergone a short course in first aid against the cruder contingencies which 110 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 might arise. Fortunately, their skill in this direction was never seriously tested; except for one or two minor mishaps, all of us kept good health and fitness throughout our stay in Canada. Sailing from Southampton to Montreal about the middle of May 1932, we journeyed by Canadian National Railways to Edmonton in Alberta, and thence north for 300 miles to MacMurray, the end PRINCIPAL STATIONS Arouno tre NORTH POLAR CAP v7 FUNCTIONING ovuring 1932 ~5. aoe \\id pare he Lae ue ae eae > \ 7 ae BOF no, Tolle Isle ON Wi ‘ ax et ie . Ficurn 1.—Distribution of main observing stations around the North Polar Cap. The dotted line indicates the supposed position of the zone of maximum auroral frequency deduced from observations before the Second Polar Year. of the once-weekly railway service, and starting point of the river and lake transport of the Hudson’s Bay Co., used for distributing stores to its trading stations in the Mackenzie River district of northwest Canada. In the shallow-draft, stern-wheeled boat, Northern Echo, we chugged our way northward down the river Athabaska, across the lake of that name, and then down the Slave River till we came to Fort Fitzgerald, where 16 miles of rapids make the river impassable. Our freight, comprising 16 tons of POLAR YEAR EXPEDITION—STAGG tit instrumental equipment and foodstuffs, had gone ahead of us, but we caught up on it at Fort Smith at the lower end of the rapids along which it had been transported by a portage road. From Smith we continued north down the Slave River and across the Great Slave Lake till we were some 1,000 miles north of Edmonton. In the early years of this century the site of the trading post at Fort Rae had been moved 25 kilometers farther north into the Marian Lake extension of the Great Slave Lake. The added facili- ties offered by staying near the trading post made us choose the new Rae for our main base. During the period of our stay, however, a site almost identical with that of the 1882-83 expedition was used as a subsidiary station in communication with the main base for photography of aurora and also in the two summers of our stay for comparison observations in terrestrial magnetism. We were fortunate in finding the north arm of the lake free from ice at an unusually early date and so arrived at the scene of our Polar Year activities by mid-June. Every minute of our time before August 1, 1932, the official date when all the Polar Year stations were due to start their activities, was occupied with the building of huts, setting up of instruments, and getting them into proper working order. By arrangement with the Hudson’s Bay Co. we were saved the building of dwelling and main observatory huts, but our magnetic work demanded two huts of special type, one for the continuously recording magneto- graphs and another for the control observations. Both of these had to be free of magnetic material, and, though our standard magneto- graphs could be completely self-compensated for temperature changes, we though it best to erect them in a chamber with as small a daily range of temperature as possible for double safety. A custom among the Dog Rib Indians in that part of Canada of deserting any dwelling-place where a member of a family has died, gave us a log shack which, when denuded of the large quantity of iron nails used by the former owners for supporting the “ wall- paper ”, formed a very serviceable outer shell for a multiple-walled, thermally insulated chamber we built within. The outer walls of this hut were subsequently mudded and heavy turf was banked up around them, so that by the time the autumn snows had made still another covering the insulation of the magnetograph chamber within was very satisfactory. In this chamber we erected three com- plete sets of magnetographs, each set recording photographically, continuously and independently the variations in the three compo- nents of the earth’s magnetic field. One set, the standard, was of the very recent pattern designed by Dr. la Cour, Copenhagen; the second set, acting as a subsidiary and run at low sensitivity, was loaned by Greenwich Observatory; and the third, also of the Copen- uly ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 hagen type, was run at quick speed for giving accurate times of inci- dence of special perturbations in the field, such as sudden commence- ments of magnetic storms. Until a year or two ago, when this quick-run magnetograph was perfected in Denmark, it was impracticable to specify times of perturbations on magnetic traces to a greater accuracy than 1 or even 2 minutes, so that such questions as the mode of propagation of world-wide sudden commencements—whether they appeared simultaneously over the earth, whether they traveled from east to west, or whether they were propagated along meridians—could not be decided with certainty. Now, among disturbances in the earth’s magnetic field during the Polar Year, a well-marked sudden com- mencement on April 30, 1933, heralding a big disturbance on May 1, was recorded on the quick-run magnetographs at most of the Polar Year stations. Preliminary measurements show that, within about 2 seconds, this movement was recorded simultaneously at places as far distant as Copenhagen, Thule in northwest Greenland, Rae in northwest Canada, and probably also at Huancayo in Peru and Watheroo in Australia. Thus an early result of the Polar Year activities may be to throw important light on this long discussed question and therefore, directly, on the mechanism producing mag- netic storms. The electric light for the recording mechanisms of this magnetic apparatus was supplied by a Delco motor generator and accumulator battery we took with us for the purpose. Of control magnetic instruments we had a double set representing the old and new systems of magnetic observing. A Kew magnetom- eter and dip circle served as comparison checks and also for parallel work at the old Fort Rae substation, where magnetic observations had to be carried out to determine the secular change since 1882; while a Smith magnetometer and dip inductor were used as the stand- ard instruments for determining horizontal force, declination, and inclination at the main base. The use of electromagnetic methods for determining the value of the earth’s magnetic field is of special ad- vantage in such a place as Rae, where magnetic disturbance is so frequent and on such a large scale. Observations which took the best part of an hour by the older technique now require only a few min- utes—provided everything goes as it should. Our meteorological equipment was very complete. Almost every instrument was run in duplicate so that records might be maintained complete in case of clock stoppage or unforeseen accident. And such safeguards proved necessary, especially where clocks running out of doors were concerned. Expecting trouble with the temperature and humidity recorders in the Stevenson screen in the winter months, we POLAR YEAR EXPEDITION—STAGG 1138 took clocks which had been specially designed to function at low temperatures; we also had some lubricating oil alleged to have a very low freezing point. But the oil froze in its bottle when put. outside the door in midwinter, and the low temperature clocks gave much more trouble than, and were indeed ultimately discarded in favor of. ordinary clocks used at meteorological office stations, after they had been completely overhauled and cleaned of every trace of lubricant. For future work where clocks are required to run continuously and regularly at low temperatures, much more attention should be paid to the design of the balance wheel and escapement movement. Our Dines anemometer erected over the main observing hut roof worked very satisfactorily. Instead of galvanized iron tubing to convey the pressure and suction surges from the head to the recorder, we used hose piping. This stood up to the cold admirably and much eased the process of erection. Only once or twice in the early days of winter had we difficulty with the water of the recorder freezing. A cupboard into which we could put a Valor heating stove was built completely around it, and when the temperature of the hut showed signs of falling below 32° F., the lighting of the stove insured safety. A greater cause of trouble in the running of the recorder was the drying of the pen. Throughout the winter months, when there was probably no unfrozen water surface nearer than the Arctic Ocean, to the north, absolute humidity generally was very low, and this, added to the dry heat produced by a large iron box-stove burning wood fuel, made the air in the hut so extremely dry that many ordinary operations became difficult. In particular, the capillary action of the surface of the anemograph record in drawing the ink from the pen seemed almost to be prohibited. A great many remedies were tried, but none was wholly satisfactory. The recording of snowfall has its own pitfalls. Even to esti- mate the total fall over a 24-hour period is difficult where the snow is fine, dry, and powdery, and so liable to drift with the slightest wind. We had a continuously recording snow recorder of the Hell- man-Fuess type as well as a rain gage converted into a snow gage, and two or three snow poles distributed around our station, but the days on which we got agreement between any two of these were exceptionally few. An attempt was made to estimate the drift snow by arranging a box with vertical circular opening and a system of baffle plates to be automatically turned into the wind, but the con- tributions to knowledge from this bit of our gear are probably negligible. An important aspect of the meteorological program was our aero- logical work, and for that we required a considerable stock of hydro- gen. The very long and expensive overland route to our station in Canada made the transport of hydrogen in cast steel cylinders 114 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 prohibitive, and to produce it by the calcium hydride process was too costly in the quantities we required. Captain Rogers, of the Royal Airship Works at Cardington, designed an apparatus for producing the gas by the interaction of hot caustic soda on finely granulated quartz. From the generator the gas passed through water traps into a reservoir bag, and from this it could be pumped by bellows into either the pilot balloons or ballons-sondes. An excel- lent piece of apparatus for its purpose in summer once its idiosyn- crasies were known, this hydrogen generator could be the most capricious item of our equipment in the winter months. It was hable to do anything with little or no provocation or warning. A shower of boiling caustic soda was common; Mr. Morgans, in charge of the meteorological work, and on whom almost all of this aerological work fell, escaped miraculously on one occasion when the roof of the hut was blown up, and the windows out, and parts of the ap- paratus rendered more or less permanently hors de combat. Pilot balloons were sent up at least once a day throughout the period of our stay at Rae, and the larger balloons with Dines meteoro- graphs attached on days when the pilot balloons indicated that the upper air currents were likely to carry them into a part of the Indian reserve through which trapping and hunting trails mainly passed. The recovery of the meteorographs was one of our very serious problems. For, except for the few Indian trails winding through the bush from Rae to the Barren Lands and Bear Lake trapping grounds in the north and down the lake shore toward the Yellow Knife estuary in the southeast, the country around our main base was almost completely uninhabited. To have attempted to hunt for the instruments ourselves, even if we had had double the personnel we actually had, would have been wholly impracticable because of the difficult nature of the bush country. And even the project— which we very seriously contemplated—of transporting all our aero- logical equipment 100 miles down to the main lake, we finally saw would not materially help our chances of recovery. So we were forced to rely on our pilot balloon and nephoscope observations (and these after all can tell us very little of where a meteorograph may be carried by the time it gets well into the stratosphere) indicating that, at any rate during the early stages of its journey, the ballons- sondes would be moving over areas where there was a chance of a few isolated Indians on the trail. To increase the chance of the meteorographs being found a long brightly colored tape was tied to each one and the Indians were encouraged to keep their eyes open for them by promise of a substantial gratuity. Further, by offering presents (illegally, as it turned out) from our small liquor store to the traders of the settlement to whom their Indian customers might bring the meteorographs, we hoped to encourage them to continue re- POLAR YEAR EXPEDITION—STAGG 115 minding the Indians of the value we put on the recovery of the instruments. When we went out to Canada we were not sanguine of retrieving any of the meteorographs, but we hoped for two; and, alas, two only we got. Both of these were from balloons released in winter condi- tions when the air temperature was about —30° C., and both the records are fortunately very good. They show that in both ascents the instruments attained heights of approximately 16 kilometers, passing through a well-marked tropopause at 8.5 kilometers with a temperature about —60° C. Since the meteorograph records are engraved on silvered plates which do not perish for many years, and since, too, the uncontami- nated nature of the atmosphere in that part of Canada will help preserve them, there is always the chance that the remainder of our meteorographs which fell into the bush will yet be discovered and forwarded to us. During the 13 calendar months of the Polar Year that ended on August 31, 1933, we continued complete meteorological observations according to the International Code every 3 hours, and during most months of that year observations of cloud every hour. The object in maintaining complete records and observations of all the meteoro- logical elements was much less to collect data for the making of climatological averages than to be able to supply detailed informa- tion about the weather and conditions in the atmosphere at any time. This, along with similar information from other cooperating sta- tions, would allow the general meteorological situation over wide areas to be reconstructed and investigated synoptically. The sum- mary of our temperature records is, however, of general interest. This confirms our experience that the winter of 1932-33 at Fort Rae was characterized less by extremes of low temperature reached than by the protracted steadiness of the cold. The mean temperature for the 7 months ending April 30 was —20° C., the contributions to this mean from January and February being both about —31° C. On individual days the lowest mean was —40° C. Day temperatures during the short summer comprising the latter part of July and August not infrequently rose to 20° C. Over the 12 months ending September 380, 1933, the mean temperature at Rae was —7.3° C. com- pared with —6.2° C. for the corresponding period at the old Fort Rae station in the first polar year 50 years ago. Observations in atmospheric electricity formed one of the other mainsubdivisions of our program of work, and these Mr. Sheppard had in his particular care. For the maintenance of continuous rec- ords of atmospheric potential gradient we used a Benndorf electro- graph and a polonium collector. To make up for the rather quick 111666—35——9 116 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 rate of decay of the polonium, additional collectors were fitted sym- metrically to the boom throughout the year so that the rate of pick-up of potential remained not less than a safe limit. The control measurements of the potential gradient were made over a level stretch of rock using the Simpson stretched wire method. Twice a day whenever possible, at 9 h. and 15 h. local time, measure- ments were made of the air-earth current, using a Wilson guard- ring electrometer modified to incorporate a Lindemann electrometer, and of small ion content of the air by an Ebert aspiration electrom- eter, also modified by Mr. Sheppard. On almost all days while these measurements were being made the number of Aitken nuclei in the atmosphere were counted by an Aitken counter. During the spring months series of experiments were made over periods of 24 hours to determine the nature of the diurnal variation of the air- earth current, ion content, and Aitken nuclei, as well as of the rate of production of ions near the ground. Though some of Mr. Morgan’s meteorological instruments had been functioning continuously from July 1, it was nearer August before the magnetographs had settled down in their new quarters, but by the first of that month, the zero hour for the general Polar Year operations, all was in working order. Since by that time the evenings were fast drawing in, we set about finding a means of maintaining communication between our main base and the substation, the site of the 1882-83 activities, 15 miles down the lake to the southeast. For a fourth and impor- tant item in our program was the simultaneous photography of suitable types of aurora at two ends of a base-line, to allow the height and orientation of the aurora to be measured from the ap- parent displacement of the same piece of aurora against its stellar background on pairs of synchronously exposed plates. To have the two-way communication which is almost necessary for this work, we had taken a supply of Silmalec wire made for us by the British Aluminum Co., and specially insulated by Henleys Cables, Limited. In its final form the wire weighed only about 23 pounds per mile. This we hoped to erect down the lakeside between the two stations, using the spruce and birch trees for support. But on detailed recon- naissance the shore was found to be so broken and irregular that to have followed the shore would have exceeded our length of cable, if not also our amateurish capabilities in erection of telephone lines. So we decided to wait till the lake had just frozen and in the mean- time, that is between August and October, we used two small wire- less transmitting and receiving sets. Though the simultaneous photo- graphic work could, in default of other means of communication, have proceeded by this means with difficulties and inconveniences and probably much loss of effective aurora, we started to erect the tele- POLAR YEAR EXPEDITION—STAGG iWiy/ phone line as soon as the ice on the lake was safe for working on. In the bush immediately behind the two stations the wire was hung from the taller spruce trees bared of their longer branches, and on the 8 to 10 miles of open lake, poles cut from spruce or birch trees along the lakeside and let into the ice sufficiently far to be frozen solidly in position, formed the bases of support. It was not prac- ticable to lay the cable on the ice, partly because the high specific inductive capacity of ice would have amounted to earthing the cable as it became buried in the ice by its own weight, and partly because a winter trail for Indians passes up the lake between the two sta- tions. The cable would very probably have been inadvertently cut by the passage of dog sleighs over it. In this work of cable laying we all had a hand, but Mr. Stephenson with his experience of dog- sleigh work gained in Greenland was invaluable in the open lake work of providing the poles from the lakeside, and Mr. Grinsted looked after all the technical details. Most of the erection was done at temperatures between —5° C. and —15° C.; it was a time of intro- duction to the experience of minor frost bites for some of us. At the two stations the observers operating the cameras, designed for auroral photography by Professors Stérmer and Krogness of Norway, were equipped with telephone headgear and breast-plate microphones, supplied by Messrs. Siemens, Ltd., so that the hands were free for manipulating the camera and plates. The microphones were fitted with auxiliary diaphragms of cellophane supported over the working diaphragm to prevent accumulation of hoar frost and ice crystals obstructing its movement. ‘These cellophane diaphragms were exceedingly useful when working out-of-doors for periods of a few hours at temperatures down to —35° C. Using the telephone system throughout the most rigorous winter months, and taking turns at manning the substation, we continued photographing aurora till the melting of the ice in spring undermined the supports and finally allowed the whole line to break up. Alto- gether we got about 4,700 pairs of photographs, of which probably 75 percent will be suitable for measurement. In addition to this side of the auroral work an almost continuous log was maintained of all activity when it was dark enough to be seen. It was not infrequent in midwinter for aurora to continue uninterruptedly for 15 hours; and, despite the fact that the winter of the Polar Year was very near the minimum of the cycle of solar activity, aurora was observed at some time on every night almost without exception during the autumn, winter, and spring months when sky conditions were suitable. During our 15 months’ stay at Rae we had frequent contact with the outside world; indeed by wireless it could have been made con- tinuous. In 1930 a reputedly rich discovery of gold and pitchblend 118 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 ores on the southeast shores of the Great Bear Lake to the north of us led to a “rush ” of prospectors and miners to stake claims, so that, whereas up to that year Rae had been one of the most isolated trad- ing posts of the Hudson’s Bay Co., in 1930 it suddenly developed into a fueling station for aeroplanes passing from the south to the Great Bear Lake mining camps. By the time we left there was a fairly regular mail service during the months when planes could use either skis or floats, so that we had the very questionable benefit of frequent contacts with the outside world. During the summer months, and at Christmas and Easter too, the Fort is a meeting-place of the Indians of the Dog Rib, Bear Lake, and Yellow Knife tribes. These come in from their hunt to barter the fox, martin, muskrat, and other fine grades of fur for their crude necessities of existence. Though at times it was annoying to see these Indians gather round when our balloons were being inflated, and gloat with glee, so it seemed, with the prospect of seeing them burst, they were a wholly inoffensive set of people, simple and contented with their lot, wistfully sympathetic with, if not openly amused at, our activities. We continued our observations at Fort Rae till early September 1933, so that we could have data covering very completely and con- tinuously the main elements in meteorology, terrestrial magnetism, atmospheric electricity, and aurora for the full Polar Year. And now the less exciting, but none the less valuable part of the work remains to be done—the reduction of the data brought home and their adequate interpretation and discussion. This must be a matter of years. For it will not be till the corresponding material from all the other cooperating stations in the network functioning along similar lines during the Polar Year is available that the true significance of events at any one station can even be partially appreciated. Not till this is done will it be possible to say whether our work at Rae was successful. But whatever the verdict of the future may be, I, as the person privileged to lead the party, would lke to take this oppor- tunity of expressing my thanks publicly to my colleagues. On such a purely scientific expedition, with the numbers cut to a minimum and with such a full program of activities, every man had to pull his full weight, and at Rae every one did so. That the observational material and records we gathered are as complete as they have turned out to be is due entirely to the splendid support given me throughout the period of our stay in Canada. Smithsonian Report, 1934.—Stagg PLATE 1 Copyright photograph by Photopress, Ltd. 1. MEMBERS OF THE POLAR YEAR PARTY PHOTOGRAPHED AT KEW OBSERVATORY. Reading from left to right: W. A. Grinsted, A. Stephenson, P. A. Sheppard, J. M. Stagg, W. R. Morgans, J. L. Kennedy. 2. ONE CORNER OF THE MAIN METEOROLOGICAL HUT. Showing (from left to right) part of the Dines anemograph and lower end of the mast, the Benndorf elec- trograph, the Ebert and Wilson instruments, and, on the right, the wireless transmitter and receiver used to maintain communication with the substation before the telephone line was erected. ALV 1d LUM SIVvolDOnOdOsaN SH “qny 94} VPISUT SI SVq ITOAIOSaI oYL, “SNLVEVddVY ONILVYANSD NASOYUGAH AHL HLIM SNVYVSYOW YY M YW iL BBrIG—'pCg| ‘Woday wetuosyztwg | ] i PROTIUM—DEUTERIUM—TRITIUM THE HYDROGEN TRIO* By HueuH 8S. TAyLor David B, Jones professor of chemistry, Princeton University [With 3 plates] Three months before the outbreak of war in 1914 an international scientific race had just been concluded. Soddy of Aberdeen had found that radio-lead from thorium sources had an atomic weight of about 208. Richards and Lembert in Harvard and Hoénigschmidt in Vienna had shown independently that radio-lead from uranium sources had an atomic weight of about 206. Ordinary lead was known to be about 207. Soddy’s concept that substances could exist with identical, or practically identical, chemical and spectroscopic properties but different atomic weights was established. Soddy suggested a name for such substances, isotopes, because, though dif- ferent in mass, they occupied the same place in the chemist’s periodic table of the elements. We know now that isotopes of the same ele- ment have the same net positive charge on the nucleus and the same system of external electrons. It is the net nuclear charge, not the mass of the nucleus, which determines the position in the periodic table. Aston, who after the war returned to the Cavendish Laboratory in Cambridge, England, developed a mass spectrograph to determine masses of individual charged particles, and in November of the year 1919 supplied definite proof that the rare gas, neon, existed in at least two isotopic forms of masses 20 and 22. He thus extended the concept of isotopes to elements which were not radioactive in their origins. There followed a decade of activity in which, with the mass spectrograph progressively refined, an increasingly large num- ber of elements were shown to be isotopically complex. There are, for example, 11 isotopes of tin. Some elements persistently proved to be simple. Carbon, oxygen, and hydrogen were among those so regarded at the end of the 10-year period. 1 Reprinted by permission from The Scientific Monthly, vol. 39, pp. 364-372, October 1934. 1) 120 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 Early in 1929 the complexity of oxygen was established by Giau- que and Johnston of California, using a novel method of attack, by examining the absorption of light by air. They found absorption bands which were interpreted as belonging to compounds containing two new oxygen isotopes, one of mass 18 and a much rarer one of mass 17. Oxygen, of mass 16, had been used as the standard of mass reference for all the other elements both for historical reasons and because of its assumed simplicity. Its established complexity at once raised doubts as to the simplicity of carbon and hydrogen. In the case of the former, the doubts were resolved by the discovery, in 1929, of a rare isotope of mass 13 by Birge and King, again from a study of the band spectra of gaseous carbon compounds, among others that of carbon monoxide. Birge and Menzel calculated that discrepancies between the chemical atomic weight and the mass spec- trograph value for hydrogen would be resolved if hydrogen contained about one part in 4,500 of an isotope of mass 2. It was this theoretical calculation which provided the spur for an experimental search for such an isotope by Urey, Brickwedde, and Murphy, jointly, at Co- lumbia University, and the United States Bureau of Standards. They announced early in 1932 that, by fractional distillation of liq- uid hydrogen, the heavier isotope concentrated in the residue, and that its presence could be demonstrated by the appearance of a faint spectral line in the hydrogen discharge near the ordinary line of atomic hydrogen and spaced from it at such a distance as would be demanded theoretically for an atom with a charge of unity (that is to say a hydrogen isotope), but having a mass of 2. Atomic weight determinations, mass spectrographic and lght absorption measurements only demonstrate the existence, the rela- tive abundance and the masses of isotopes. The practical identity of their chemical properties, emphasized at the outset by Soddy, had been utilized in the case of radioactive isotopes for chemical indicator purposes; the desirable goal of the scientist, the separation of the isotopes of an element and the separate examination and comparison of their properties, remained until a year ago unattained. An enor- mous amount of effort has been expended in the attempts at sepa- ration. These must be based on differences in properties which depend essentially on mass or on chemical reactivity. For a decade and a half prior to 1933 a variety of trials were made. Separation was attempted by fractional diffusion, by thermal diffusion, by cen- trifugal separation, by fractional distillation and evaporation at low pressure, by migration of isotopic ions under the influence of an electric current, by preferential excitation to photochemical reaction of one or other isotope using light absorbed by one and not the other. PROTIUM—DEUTERIUM—TRITIUM—TAYLOR 1 | The net success was vanishingly small. One or other method gave separations of one or two parts per thousand at such a prodigious expenditure of effort that the recovery of the pure components of an isotopic mixture seemed to be an unattainable objective. The hydrogen isotopes, of masses 1 and 2, represent the most favorable case, since the mass difference is 100 percent. Even in this case the problem seemed to be discouragingly difficult when it was shown that the fractional evaporation of 40 liters of liquid hydrogen until only two liters of gas remained raised the concentration of the heavier gas only to 1.5 percent. Hertz in Germany has separated the two isotopes by fractional diffusion through special porous ma- terial to yield the separate constituents spectroscopically pure. His method, however, only yields a few cubic millimeters of gaseous product. The development which revolutionized the whole subject of isotope chemistry is due to the late Dr. E. W. Washburn of the United States Bureau of Standards. Washburn determined, late in 1931, to test the efficiency of electrolysis of water solutions as a method of concentrating the hydrogen isotopes. While his own experiments were in progress, he secured samples of water from commercial cells which had been used for several years in the electrolytic production of hydrogen and oxygen. Urey analyzed this water for him by the spectroscopic method and found an enrichment of the mass 2 isotope. Washburn himself found that the density of the water was greater than that of ordinary water by 50 parts per million, a further evi- dence of enrichment. As Washburn and Urey wrote in their joint communication “the above results are of great importance, for we now know that there are large quantities of water in these electro- lytic cells containing heavy hydrogen in relatively high concentra- tions and, also, there is available now a method for concentrating this isotope in large quantities.” Washburn’s determination of the ab- normal density of water from electrolytic cells will take rank with those classical determinations by Lord Rayleigh of the densities of chemical and atmospheric nitrogen, from which, with the work of Sir William Ramsay, there resulted the discovery of the rare gases of the atmosphere, helium, neon, argon, krypton, and xenon. The isolation of the mass 2 isotope in approximate purity was not achieved by Washburn. The race was to the swift and to those richer in available resources of apparatus and men. In rapid succession, from the University of California, Princeton, Cambridge, England, Columbia University, Frankfort, and Vienna came records of the success of Washburn’s method in producing water in which, with continued electrolysis, 30, 60, 92, 99.9 percent of all the hydrogen 122 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 atoms had a mass of 2 instead of 1. Since the mass of the molecule H,O would be 2X2+16=20, whereas ordinary water would be 2X1+16=18, it is evident that, granting equal volumes of the two molecules, the new water might have a density of 20/18=1.11. The experiments were followed by the changing density of the product, and it is now known that heavy water with hydrogen of mass 2 has a density of 1.1079 at 25° C. referred to ordinary water at the same temperature. Shortly after the isolation was accomplished, Urey, Brickwedde, and Murphy christened the isotopes; hitherto this had not been necessary with isotopes, since there had been no chemistry of separate isotopes to be considered. The discoverers of heavy hydrogen sug- gested, for hydrogen of mass 1, the name protium, since this would conform with current usage of the name proton for the nucleus of the hydrogen atom. For the isotope of mass 2 they proposed the name deuterium, which, for the nucleus of this atom, suggests deu- teron or, more briefly, deuton, the nucleus of mass 2 and unit positive charge. They also suggested that, if the isotope of mass 3 were discovered, the name tritium might be considered. ‘These names have found general acceptance, except in England, where, following a suggestion from Lord Rutherford’s laboratory, the name “ dip- logen ” has been employed. The best excuse for this latter is that it gives “diplon ” instead of deuton, which latter does not find favor with the English scientists who, with colds in their heads in winter time, may confuse deuton with the “neutron”, the particle of mass 1 and zero charge. Considerable discussion has arisen as to the symbols to be employed. Previous custom has sanctioned H?, H?, and H? for the symbolic representation. ‘There is, however, an increasing use of H for H,, of D for H, and of T for H;. For- tunately, D and T have not hitherto been used as symbols for any elements; also, D stands, equally well in England and elsewhere, for both deuterium and diplogen. Yor the technique of preparation of pure heavy water or deuterium oxide, the Princeton procedure may be cited, since, in this manner, about 13 tons of commercial electrolyte corresponding to upwards of 50 tons of ordinary water have already been treated to yield approximately one pound of the purest heavy water. About 15 galions of commercial liquor are electrolyzed daily to one-fifth vol- ume in a battery of 960 cells using nickel anodes and iron cathodes. The residue is distilled to remove excess electrolyte, and the distillate after addition of alkali is passed to the second stage, a unit of 160 cells shown in plate 1, where it is again electrolyzed to one-fifth volume. These two stages concentrate the deuterium from 1 part in 1,600 to 0.25 percent, and 1 percent, respectively. From the third stage onward a modified form of electrolysis is employed in which PROTIUM—DEU TERIUM—TRITIU M—TAYLOR 123 the evolved hydrogen (containing deuterium) and oxygen gases are recovered as water and passed back to the preceding stage of elec- trolysis. The experimental arrangement is shown in plate 2. The successive stages handle successively smaller volumes of water, the concentration of deuterium in which rises by steps from 1 percent to 4, 13, 35, 95, and 100 percent D,O. The electrolytic fractionation factor is about 5, that is to say, the gas evolved is about one-fifth as concentrated in deuterium as the water from which it is evolved. Hence the separation that is achieved. The product has unique and characteristic properties. Its density relative to ordinary water at 25° C. is 1,1079. It melts at 3.82° C. and boils at 101.42° C. It has a maximum density, not at 4° C. as with ordinary water, but at 11.6° C. It is 25 percent more viscous than ordinary water at 20° C. but has a smaller surface tension. Salts are less soluble in it by about 10 percent, and the electrical conductance of salt solutions is less than in light water. There are three kinds of hydrogen molecules that can arise from hght and heavy hydrogen atoms, namely, H, molecules, D. molecules, and the mixed molecule HD. To analyze mixtures of such gases a special mass spectrograph has been developed by Dr. Bleakney, of the Princeton Physics Department. It is evident that the molecules just discussed will give rise to ions of masses 2\(H,*), 3A(HD*), and 4\(D.*). In addition to these, atomic ions of masses 1 and 2 (H* and D*) can also arise and, from these, triatomic ions (HHH*) of mass 8, (HHD*) of mass 4, (HDD*) of mass 5 and (DDD*) of mass 6. Bleakney’s method permits him to sort out these various possibilities so that he can estimate how much protium (H) and how much deuterium (D) is present in a given sample. Figure 1 shows the results of one such analysis of a deuterium-rich sample. Using such a method of analysis it has been found that the deute- rium content of normal rain water is 1 part in 5,000 of the total hydro- gen present. This is a much greater abundance of deuterium than is present in the chromosphere of the sun as spectra at the last eclipse definitely showed; it points to a tremendous preferential loss of ight hydrogen during the earth’s formation. The announcement by Lord Rutherford of the synthetic production of hydrogen of mass 3, tritium (T) by bombardment experiments of deuterium with highspeed deutons lent considerable interest to a determination by the Princeton Physics Department of the tritium content of the purest deuterium oxide water prepared in the Frick Chemical Laboratory. With a new and specially refined mass spectrograph it has now been shown that our purest heavy water contains approximately 1 tritium to 200,000 deuterium atoms. This means that, in ordinary water, the tritium con- tent is not more than 1 part ina billion. Tritium, therefore, becomes the youngest and rarest of all the isotopes yet discovered in naturally 124 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 occurring substances. Since heavy deuterium water costs, at a con- servative estimate, $5 per gram, it is evident that, with a 100 per cent efficiency of recovery of its tritium content, pure tritium water, T,O, would cost at least $1,000,000 a gram or water roughly 20 times the cost of radium. Such are the paradoxes of modern isotope chemistry. A Daa} Intensities of tke Tons a es + (uDD)xiot (BPD) «7 O° Hxio” (HW a)xio” (HD) / 2 3 4 Masses of the Ions Ficurp 1.—Diagrammatic representation of an analysis by the mass spectrograph of a gas sample rich in deuterium. Each peak represents the abundance of the ion of mass given along the horizontal axis of the graph. The scale for the ions H+, (HH)t, (HDD)+, and (DDD)+ is multiplied by the amounts shown against each peak to Permit their representation on the same diagram in spite of their great rarity. The analysis yields 98 atom percent D and 2 atom percent H. 5 6 Using the same method of analysis it is possible to follow the rate of reaction of one isotope of a given element with its one isotope. It has been shown, for example, that H, molecules will react with D, molecules to form HD molecules at temperatures as low as that of liquid air, with catalysts such as chromium oxide and nickel, which are active in catalytic hydrogenation processes. These results indicate that the high temperatures necessary in industrial syntheses such as those of ammonia or wood alcohol are required not for the activation of the hydrogen but for the activation of the molecules with which the hydrogen has to react. Ifsurfaces can be found as active toward these molecules as present available surfaces are with respect to hydrogen, PROTIUM—DEU TERIUM—TRITIUM—TAYLOR 125 tremendous improvements would be possible in such industrial opera- tions, under much simpler working conditions. Deuterium points the direction which research in technical catalysis must take. Biologically, heavy water has proved to be of the utmost interest. Seeds of the tobacco plant do not germinate in heavy water. Fresh- water organisms such as tadpoles and guppies die quickly when placed in heavy water. Unicellular organisms, such as paramoecium or euglena, are more resistant, but are eventually killed. The lumines- cence of bacteria is modified in heavy water media, and the rate of respiration markedly reduced. Yeast ferments sugar in heavy water at only one ninth the rate in ordinary water. The enzyme catalase present in the blood stream and whose function it is to detroy hydro- gen peroxide does so at only one-half the normal rate in 85 per cent heavy water. The action of the heavy water may be likened to that of a generally unfavorable environment leading to progressive changes in the cell. It would seem that the changes observed are the result of differential effects on the rate of biochemical reactions, ex- amples of which have just been given in respect to enzyme reactions. The use of heavy water as an indicator of reaction mechanism in biological systems is evident from reports of recent English work in which it has been shown, by experiments conducted in heavy water, with organisms such as B. coli and B. aceti, that the present accepted mechanisms for their activity need to be modified in the light of re- sults obtained with media containing deuterium instead of hydrogen. The known compounds containing hydrogen are numbered in the hundreds of thousands. It is evident that an overwhelming program of research replacing hydrogen by deuterium is possible. Judiciously conducted, such a program will aim at the preparation of materials with which problems in physicochemical science may be tested. There are already the beginnings of such a program to be recorded. A number of exchange reactions between heavy water and different substances have thrown light on the problems of mechanism involved. Thus, ammonia gas, NH;, exchanges very rapidly with heavy water, D,O, to give ammonia in which the hydrogen atoms are replaced by deuterium atoms to an extent depending on relative concentrations. In cane sugar, however, only about half the hydrogen atoms are readily replaced and these atoms are those present in the molecules as hydroxyl (OH) groups. Acetylene, C,H., and acetone CH; COCHs, do not replace their hydrogens for deuterium in acid solu- tions or in plain heavy water but do so more or less readily in basic solutions. The former exchange indicates definitely the acidic nature of acetylene. The latter demonstrates that acetone in basic solutions exists partially in another form CH;*COH: CH), which is acidic in nature due to the H attached to oxygen. In acetic acid CH,;COOH only the final acidic H is readily replaceable by D. In a compound 126 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 such as nitroethane, CH,CH.NO,, the two hydrogen atoms next to the NO, group are replaceable by deuterium in basic solutions of heavy water. In this case the rate of reaction can be measured and it has been shown that H atoms leave this molecule more easily in the heavy water solutions than they do in light water solutions. Similarly, cane sugar is broken up by reaction with heavy water faster than by light water. In other reactions the velocity is slower in heavy water. The accelerating or retarding effect obtained is used by the chemist to de- cide the detailed picture of what is occurring in such solutions. With deuterium atoms as labeled hydrogen atoms, much can be learned about these detailed occcurrences; and what is found for deuterium must also occur with hydrogen under the same conditions, even though, without the label, this cannot be demonstrated. Reactions of deuterium and deuterium compounds which are slower than those of hydrogen are due to the fact that the lowest energy states (the zero-point energies) of the former are less than those of the latter. To become equally activated, by heat or ight, deuterium must receive greater increments of energy; vice versa, under equal energy condi- tions the deuterium compounds will in general be less reactive. In cases where this does not hold it is to be concluded that reaction does not involve molecules of the deuterium compound, but rather an atom or an ion. Comparative velocity measurements are, therefore, of great importance theoretically. In the physics laboratory deuterium is being put to spectacular use as a projectile in atomic transmutation. Immediately after the isola- tion of deuterium the nuclei or deutons were so employed to bombard lithium, the results showing them to be much more effective missiles than protons. Two processes are possible with the isotopes of lithium of masses 6 and 7. gLi® + ,D? = 2,He* et 9 lies an The subscript to the left represents the nuclear charge; the super- script is the mass. Here also on’ represents a neutron of zero charge and unit mass. Helium of mass 4 and charge 2 is the other product. Experiments in Cambridge under Lord Rutherford suggested that deutons could be used to bombard deutons and produce new forms of matter. Here, also, there are two possibilities. | Die eg Bd bea) Sb ,D?+,D?=.He?+ on, In the first, transmutation gives two hydrogen atoms, one of mass 1, the other of mass 3, in other words, tritium. In the second, the change is to a helium isotope of mass 3 and charge 2 and a neutron PROTIUM—DEUTERIU M—TRITIUM—TAYLOR 17. of mass 1 and zero charge. Both of these changes have now been decisively demonstrated not only by the methods of Rutherford involving measurements of the tracks of particles; they have been employed to produce these rare isotopes “in quantity.” Samples of deuterium after subjection to such atomic bombard- ment in apparatus shown in figure 2 and plate 3 have been found by the Prince- ton physicists to contain concentrations of tritium 40 times greater than that of the deuterium initially. Similarly, the production of helium isotope of mass 3 has also been shown. In each case the method of analysis involves the sensi- tive mass spectrograph al- ready discussed. Deutons also are being used as the projectiles for the produc- tion of artificially radio- active light atoms, the new field of physics developed only this last year by M. Joliot and his wife, Mme. Curie Joliot, first with al- pha particles, next with protons and neutrons, and now also with deutons. That the pace of this scientific development is prodigious all must realize when they remember that only a year ago the deu- terium isotope was not yet isolated. Today it has a WOK Y ‘ vooede rz AW Tigurm 2.—Diagrammatie sketch of transmuta: tion tube. Deuterium in the upper half is ionized and the deutons are led through the slit or canal, between the shaded areas, to the lower half of the tube in which they collide, under high potential, with deuterium atoms and molecules to give the observed transmuta- tions to tritium and to helium 38. The gas is constantly circulated between the upper and lower halves of the canal ray tube. still rarer brother, tritium; it has itself given rise to this and to other new isotopes, some radioactive, some not; it has made possible a new branch of chemistry, the chemistry of isotopes, which already has markedly enriched our knowledge of general and physical chemistry ; it is a potent weapon of attack also on physiological and biological problems. Dene te S i pe ra i Filh F Mr RI BP #7 CN on eis n ines a cee A ON Yor, Bt ih ahanane a a eh ae \ ¥ | Sa A ' ~| nt A. ; Woe a ‘ Aly An 4 o Obs x ‘ ~ a wren Ms rh Laat, © eh Ls Woh iy (Ape hs ; r 4 on ‘ ay rr eh ee aA td ay 4 aie OL RR i in. wits) Why Leva T bartunta, & AA ca : VF Mey : ee Phe! | we \ * ays iid’ ws H 0 25 1a: 4M q ’ ‘ " } rie: hoes , ry a vy *) 18 UMOYS SI SIONDIT 9uTpeyye jo uc -uas0IpAY POA[OAD 9y4 JO AIBAODOI SUIAO[AUId ‘jIUN JeT[BUIS B ST ‘Z 9Je[d UI [IeJop UL UMOYS ITM4sip 10} [Ws teaddod oy, 9“SUOTJN[OS pe{v1.UGDTIOD BIOL IOJ P9sn Pav SsoINjXIM WINtId4Inep ‘gq YURL ‘SISA[OIQO0/0 JO 9384S PUOdDIS 94} JO} SJlUNn SUIBIUOD JYSI 0} WY yueRy, “YALVM AAVAH SAO NOILVYLNADNOD DILATOYULOATA AO MAIA IVWYANAD | a1VvV1d “H YUL} UL p9[00d-10}VM STOSSOA SISA[O1499]9 9YY UL SUIUIVUIOI ONPISeL Peyotius 9y} ‘C Ul pd9zo9][00 puw pesuepUOd SI 19}BM eyL “Oo jef xoidd 8 4e pound oie pus ‘g sdv1j uolsojdxo oy} Ysno1yy ssed ‘10}400 YUEqIOSGB SUIUTBIUOD Y S19M0} OY4 UL AvACS UOJ Pod] OB UISAXO PUB DINTIeynNep-uds0IpAY ou, “NOILVWSNAGNOD AGNV NOILSNEWOD AG NS3SAKO GNV WNIYSLNAG-NS390Y¥GAH 3O AYSAAODSY HLIM SISATOYN LOA19 ec ALV 1d Joj|Ae [| —*peg| *q40day uetuosyziwiG Smithsonian Report, 1934.—Taylor PEATE 3 GENERAL VIEW OF APPARATUS EMPLOYED IN PALMER PHYSICAL LABORATORY, PRINCETON UNIVERSITY, FOR TRANSMUTATION OF DEUTERIUM INTO (A) TRI- TIUM AND HYDROGEN, (B) HELIUM OF MASS 3 AND NEUTRONS. The long glass tube shown to the left of the center of the photograph is the actual location of the transmu- tation process. This unit is shown diagrammatically in figure 2. SOME CHEMICAL ASPECTS OF LIFE’ By Sir FreprrRicK GOWLAND HOPKINS, Pres. R. S. I The British Association returns to Leicester with assurance of a welcome as warm as that received 26 years ago, and of hospitality as generous. The renewed invitation and the ready acceptance speak of mutual appreciation born of the earlier experience. Hosts and guests have today reasons for mutual congratulations. The Associa- tion on its second visit finds Leicester altered in important ways. It comes now to a city duly chartered and the seat of a bishopric. It finds there a center of learning, many fine buildings which did not exist on the occasion of the first visit, and many other evidences of civic enterprise. The citizens of Leicester, on the other hand, will know that since they last entertained it the Association has cele- brated its centenary, has four times visited distant parts of the Empire, and has maintained unabated through the years its useful and important activities. In 1907 the occupant of the Presidential Chair was, as you know, Sir David Gill, the eminent astronomer who, unhappily, like many who listened to his address, is with us no more. Sir David dealt in that address with aspects of science characterized by the use of very exact measurements. The exactitude which he prized and praised has since been developed by modern physics and is now so great that its methods have real esthetic beauty. In contrast, I have to deal with a branch of experimental science which, because it is concerned with living organisms, is in respect of measurement on a different plane. Of the very essence of biological systems is an in- eludible complexity, and exact measurement calls for conditions here unattainable. Many may think, indeed, though I am not claiming it here, that in studying life we soon meet with aspects which are nonmetrical. I would have you believe, however, that the data of modern biochemistry which will be the subject of my remarks were won by quantitative methods fully adequate to justify the claims based upon them. 1 Presidential address before the British Association for the Advancement of Science, Leicester, 1933. Reprinted by permission from the Report of the Association for 1933. 129 130 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 Though speculations concerning the origin of life have given in- tellectual pleasure to many, all that we yet know about it is that we know nothing. Sir James Jeans once suggested, though not with conviction, that it might be a disease of matter—a disease of its old age! Most biologists, I think, having agreed that life’s advent was at once the most improbable and the most significant event in the history of the universe, are content for the present to leave the matter there. We must recognize, however, that life has one attribute that is fundamental. Whenever and wherever it appears the steady in- crease of entropy displayed by all the rest of the universe is then and there arrested. There is no good evidence that in any of its manifestations life evades the second law of thermodynamics, but in the downward course of the energy-flow it interposes a barrier and dams up a reservoir which provides potential for its own re- markable activities. The arrest of energy degradation in living nature is indeed a primary biological concept. Related to it, and of equal importance is the concept of organization. It is almost impossible to avoid thinking and talking of life in this abstract way, but we perceive it, of course, only as manifested in organized material systems, and it is in them we must seek the mechanisms which arrest the fall of energy. Evolution has estab- lished division of labor here. From far back the wonderfully effi- cient functioning of structures containing chlorophyll has, as every- one knows, provided the trap which arrests and transforms radiant energy—fated otherwise to degrade—and so provides power for nearly the whole living world. It is impossible to believe, however, that such a complex mechanism was associated with life’s earliest stages, Existing organisms illustrate what was perhaps an earlier method. The so-called “autotrophic” bacteria obtain energy for growth by the catalyzed oxidation of materials belonging wholly to the inorganic world, such as sulphur, iron, or ammonia, and even free hydrogen. ‘These organisms dispense with solar energy, but they have lost in the evolutionary race because their method lacks economy. Other existing organisms, certain purple bacteria, seem to have taken a step toward greater economy, without reaching that of the green cell. They dispense with free oxygen and yet obtain energy from the inorganic world. They control a process in which carbon dioxide is reduced and hydrogen sulphide simultaneously oxidized. The molecules of the former are activated by solar energy which their pigmentary equipment enables these organisms to arrest. Are we to believe that life still exists in association with systems that are much more simply organized than any bacterial cell? The very minute filter-passing viruses which, owing to their causal rela- CHEMICAL ASPECTS OF LIFE—HOPKINS ot tions with disease, are now the subject of intense study, awaken deep curiosity with respect to this question. We cannot yet claim to know whether or not they are living organisms. In some sense they grow and multiply, but, so far as we yet know with certainty, only when inhabitants of living cells. If they are nevertheless living, this would suggest they they have no independent power of obtaining energy and so cannot represent for us the earliest forms in which life appeared. At present, however, judgment on their biological significance must be suspended. The fullest understand- ing of all the methods by which energy may be acquired for life’s processes is much to be desired. In any case every living unit is a transformer of energy however acquired, and the science of biochemistry is deeply concerned with these transformations. It is with aspects of that science that I am to deal and if to them I devote much of my address my excuse is that since it became a major branch of inquiry biochemistry has had no exponent in the Chair I am fortunate enough to occupy. As a progressive scientific discipline it belongs to the present cen- tury. From the experimental physiologists of the last century it obtained a charter, and, from a few pioneers of its own, a promise of success; but for the furtherance of its essential aim that century left it but a small inheritance of facts and methods. By its essential or ultimate aim I myself mean an adequate and acceptable descrip- tion of molecular dynamics in living cells and tissues. II When this association began its history in 1831 the first artificial synthesis of a biological product was, as you will remember, but 3 years old. Primitive faith in a boundary between the organic and the inorganic which could never be crossed was only just then realiz- ing that its foundations were gone. Since then, during the century of its existence, the association has seen the pendulum swing back and forth between frank physico-chemical conceptions of life and various modifications of vitalism. It is characteristic of the present position and spirit of science that sounds of the long conflict between mechanists and vitalists are just now seldom heard. It would almost seem, indeed, that tired of fighting in a misty atmosphere each has retired to his tent to await with wisdom the light of further knowl- edge. Perhaps, however, they are returning to the fight disguised as determinist and indeterminist, respectively. If so the outcome will be of great interest. In any case I feel fortunate in a belief that what TI have to say will not, if rightly appraised, raise the old issues. To claim, as I am to claim, that a description of its active chemical 111666—35——10 132 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 aspects must contribute to any adequate description of life is not to imply that a living organism is no more than a physio-chemical system. It implies that at a definite and recognizable level of its dynamic organization an organism can be logically described in physico-chemical terms alone. At such a level indeed we may hope ultimately to arrive at a description which is complete in itself, just as descriptions at the morphological level of organization may be complete in themselves. There may be yet higher levels calling for discussion in quite different terms. I wish, however, to remind you of a mode of thought concerning the material basis of life, which though it prevailed when physico- chemical interpretations were fashionable, was yet almost as inhibi- tory to productive chemical thought and study as any of the claims of vitalism. This was the conception of that material basis as a single entity, as a definite though highly complex chemical compound. Up to the end of the last century and even later the term “ pretoplasm ” suggested such an entity to many minds. In his brilliant presidential address at the association’s meeting at Dundee 22 years ago, Sir Edward Sharpey-Schafer, after remarking that the elements compos- ing living substances are few in number, went on to say: “ The com- bination of these elements into a colloid compound represents the physical basis of life, and when the chemist succeeds in building up this compound it will, without doubt, be found to exhibit the phe- nomena which we are in the habit of associating with the term ‘life’.” Such a compound would seem to correspond with the “ protoplasm ” of many biologists, though treated perhaps with too little respect. The presidential claim might have seemed to encourage the biochem- ist, but the goal suggested would have proved elusive, and the path of endeavor has followed other lines. So long as the term “ protoplasm ” retains a morphological signifi- cance as in classical cytology, it may be even now convenient enough, though always denoting an abstraction. Insofar, however, as the progress of metabolism with all the vital activities which it supports was ascribed in concrete thought to hypothetical qualities emergent from a protoplasmic complex in its integrity or when substances were held to suffer change only because in each living cell they are first built up, with loss of their own molecular structure and identity, into this complex, which is itself the inscrutable seat of cyclic change, then serious obscurantism was involved. Had such assumptions been justified the old taunt that when the chemist touches living matter it immediately becomes dead matter would also have been justified. A very distinguished organic chem- ist, long since dead, said to me in the late eighties: “ The chemistry of the living? That is the chemistry of protoplasm; that is super- chemistry; seek, my young friend, for other ambitions.” CHEMICAL ASPECTS OF LIFE—HOPKINS 133 Research, however, during the present century, much of which has been done since the association last met in Leicester, has yielded knowledge to justify the optimism of the few who started to work in those days. Were there time, I might illustrate this by abundant examples; but I think a single illustration will suffice to demon- strate how progress during recent years has changed the outlook for biochemistry. I will ask you to note the language used 30 years ago to describe the chemical events in active muscle and compare it with that used now. In 1895 Michael Foster, a physiologist of deep vision, dealing with the respiration of tissues, and in particular with the degree to which the activity of muscle depends on its contemporary oxygen supply, expounded the current view which may be thus briefly summarized. The oxygen which enters the muscle from the blood is not involved in immediate oxidations, but is built up into the substance of the muscle. It disappears into some protoplasmic com- plex on which its presence confers instability. This complex, like all living substance, is to be regarded as incessantly undergoing changes of a double kind, those of building up and those of breaking down. With activity the latter predominates, and in the case of muscle the complex in question explodes, as it were, to yield the en- ergy for contraction. “We cannot yet trace”, Foster comments, “the steps taken by the oxygen from the moment it slips from the blood into the muscle substance to the moment when it issues united with carbon as carbonic acid. The whole mystery of life lies hidden in that process, and for the present we must be content with simply knowing the beginning and the end.” What we feel entitled to say today concerning the respiration of muscle and of the events asso- ciated with its activity requires, as I have suggested, a different language, and for those not interested in technical chemical aspects the very change of language may yet be significant. The conception of continuous building up and continuous breakdown of the muscle substance as a whole, has but a small element of truth. The colloidal muscle structure is, so to speak, an apparatus, relatively stable even as a whole when metabolism is normal, and in essential parts very stable. The chemical reactions which occur in that apparatus have been followed with a completeness which is, I think, striking. It is carbohydrate stores distinct from the apparatus (and in certain circumstances also fat stores) which undergo steady oxidation and are the ultimate sources of energy for muscular work. Essential among successive stages in the chemical breakdown of carbohydrate which necessarily precede oxidation is the intermediate combination of a sugar (a hexose) with phosphoric acid to form an ester. This happening is indispensable for the progress of the next stage, namely the production of lactic acid from the sugar, which is an anaerobic process. The precise happenings to the hexose sugar while in com- 134 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 bination with phosphoric acid are from a chemical standpoint re- markable. Very briefly stated they are these. One-half of the sugar molecule is converted into a molecule of glycerin and the other half into one of pyruvic acid. Now with loss of two hydrogen atoms glycerin yields lactic acid, and, with a gain of the same pyruvic acid, also yields lactic acid. The actual happening then is that hydro- gen is transferred from the glycerin molecule while still combined with phosphoric acid to the pyruvic acid molecule with the result that two molecules of lactic acid are formed. ‘The lactic acid is then, during a cycle of change which I must not stop to discuss, oxidized to yield the energy required by the muscle. But the energy from this oxidation is by no means directly avail- able for the mechanical act of contraction. The oxidation occurs indeed after and not before or during a contraction. The energy it liberates secured however the endothemic resynthesis of a substance, creatin phosphate, of which the breakdown at an earlier stage in the sequence of events is the more immediate source of energy for contraction. Even more complicated are these chemical relations, for it would seem that in the transference of energy from its source in the oxidation of carbohydrate to the system which synthesizes creatin phosphate, yet another reaction intervenes, namely, the alter- nating breakdown and resynthesis of the substance adenyl pyrophos- phate. The sequence of these chemical reactions in muscle has been followed and their relation in time to the phases of contraction and relaxation is established. The means by which energy is transferred from one reacting system to another has till lately been obscure, but current work is throwing light upon this interesting question, and it is just beginning (though only beginning) to show how at the final stage the energy of the reactions is converted into the mechan- ical response. In parenthesis it may be noted as an illustration of the unity of life that the processes which occur in the living yeast cell in its dealings with sugars are closely similar to those which proceed in living muscle. In the earlier stages they are identical and we now know where they part company. You will, I think, be astonished at the complexity of the events which underlie the activity of a muscle, but you must remember that it is a highly specialized machine. A more direct burning of the fuel could not fit into its complex organization. I am more particularly concerned to feel that my brief summary of the facts will make you realize how much more definite, how much more truly chemical, is our present knowl- edge than that available when Michael Foster wrote: Ability to recognize the progress of such definite ordered chemical reactions in relation to various aspects of living activity characterizes the cur- rent position in biochemistry. I have chosen the case of muscle, and it must serve as my only example, but many such related and CHEMICAL ASPECTS OF LIFE—HOPKINS 135 ordered reactions have been studied in other cells and tissues, from bacteria to the brain. Some prove general, some more special. Although we are far indeed from possessing a complete picture in any one case we are beginning in thought to fit not a few pieces together. We are on a line safe for progress. I must perforce limit the field of my discussion, and in what fol- lows my special theme will be the importance of molecular structure in determining the properties of living systems. I wish you to be- lieve that molecules display in such systems the properties inherent in their structure even as they do in the laboratory of the organic chemist. The theme is no new one, but its development illustrates as well as any other, and to my own mind perhaps better than any other, the progress of biochemistry. Not long ago a prominent biologist, believing in protoplasm as an entity, wrote: “ But it seems certain that living protoplasm is not an ordinary chemical compound, and therefore can have no molecular structure in the chemical sense of the:word.” Such a belief was common. One may remark, more- over, that when the development of colloid chemistry first brought its indispensable aid toward an understanding of the biochemical field, there was a tendency to discuss its bearing in terms of the less specific properties of colloid systems, phase-surfaces, membranes, and the like, without sufficient reference to the specificity which the influence of molecular structure, wherever displayed, impresses on chemical relations and events. In emphasizing its importance I shall leave no time for dealings with the nature of the colloid structures of cells and tissues, all important as they are. I shall continue to deal, though not again in detail, with chemical reactions as they occur within those structures. Only this much must be said. If the colloid structures did not display highly specialized molecular struc- ture at their surface, no reactions would occur; for here catalysis occurs. Were it not equipped with catalysts every living unit would be a static system. With the phenomena of catalysis I will assume you have general acquaintance. You know that a catalyst is an agent which plays only a temporary part in chemical events which it nevertheless deter- mines and controls. It reappears unaltered when the events are com- pleted. The phenomena of catalysis, though first recognized early in the last century, entered but little into chemical thought or enter- prise, till only a few years ago they were shown to have great impor- tance for industry. Yet catalysis is one of the most significant devices of nature, since it has endowed living systems with their fundamental character as transformers of energy, and all evidence suggests that it must have played an indispensable part in the living universe from the earliest stages of evolution. 136 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 The catalysts of a living cell are the enzymic structures which display their influences at the surface of colloidal particles or at other surfaces within the cell. Current research continues to add to the great number of these enzymes which can be separated from, or recognized in, living cells and tissues, and to increase our knowledge of their individual functions, A molecule within the system of the cell may remain in an inactive state and enter into no reactions until at one such surface it comes in contact with an enzymic structure which displays certain adjust- ments to its own structure. While in such association the inactive molecule becomes (to use a current term) “activated,” and then enters on some definite path of change. The one aspect of enzymic catalysis which for the sake of my theme I wish to emphasize is its high specificity. An enzyme is in general adjusted to come into effective relations with one kind of molecule only, or at most with molecules closely related in their structure. Evidence based on kinetics justifies the belief that some sort of chemical combination between enzyme and related molecule precedes the activation of the latter, and for such combinations there must be close correlation in structure. Many will remember that long ago Emil Fischer recog- nized that enzymic action distinguishes even between two optical isomers and spoke of the necessary relation being as close as that of key and lock. There is an important consequence of this high specificity in bio- logical catalysis to which I will direct your special attention. A liv- ing cell is the seat of a multitude of reactions, and in order that it should retain in a given environment its individual identity as an organism, these reactions must be highly organized. They must be of determined nature and proceed mutually adjusted with respect to velocity, sequence, and in all other relations. They must be in dynamic equilibrium as a whole and must return to it after disturb- ance. Now if of any group of catalysts, such as are found in the equipment of a cell, each one exerts limited and highly specific influ- ence, this very specificity must be a potent factor in making for organization. Consider the case of any individual cell in due relations with its environment, whether an internal environment as in the case of the tissue cells of higher animals, or an external environment as in the case of unicellular organisms. Materials for maintenance of the cell enter it from the environment. Discrimination among such materials is primarily determined by permeability relations, but of deeper significance in that selection is the specificity of the cell catalysts. It has often been said that the living cell differs from all nonliving systems in its power of selecting from a hetero- CHEMICAL ASPECTS OF LIFE—-HOPKINS 137 geneous environment the right material for the maintenance of its structure and activities. It is, however, no vital act but the nature of its specific catalysts which determines what it effectively “ selects.” If a molecule gains entry into the cell and meets no catalytic influence capable of activating it, nothing further happens save for certain ionic and osmotic adjustments. Any molecule which does meet an adjusted enzyme cannot fail to suffer change and become directed into some one of the paths of metabolism. It must here be remem- bered, moreover, that enzymes as specific catalysts not only promote reactions, but determine their direction. The glucose molecule, for example, though its inherent chemical potentialities are, of course, always the same, is converted into lactic acid by an enzyme system in muscle but into alcohol and carbon dioxide by another in the yeast cell. It is important to realize that diverse enzymes may act in suc- cession and that specific catalysis has directive as well as selective powers. If it be syntheses in the cell which are most difficult to pic- ture on such lines, we may remember that biological syntheses can be, and are, promoted by enzymes, and there are sufficient facts to jus- tify the belief that a chain of specific enzymes can direct a complex synthesis along lines predetermined by the nature of the enzymes themselves. I should like to develop this aspect of the subject even further, but to do so might tax your patience. I should add that enzyme-control, though so important, is not the sole determinant of chemical organization in a cell. Other aspects of its colloidal struc- ture play their part. Iil It is surely at that level of organization, which is based on the exact coordination of a multitude of chemical events within it, that a living cell displays its peculiar sensitiveness to the influence of molecules of special nature when these enter it from without. The nature of very many organic molecules is such that they may enter a cell and exert no effect. Those proper to metabolism follow, of course, the normal paths of change. Some few, on the other hand, influence the cell in very special ways. When such influence is highly specific in kind, it means that some element of structure in the en- trant molecule is adjusted to meet an aspect of molecular structure somewhere in the cell itself. We can easily understand that in a system so minute the intrusion even of a few such molecules may so modify existing equilibria as to affect profoundly the observed behavior of the cell. Such relations, though by no means confined to them, reach their greatest significance in the higher organisms, in which individual tissues, chemically diverse, differentiated in function and separated in space, so react upon one another through chemical agencies trans- 138 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 mitted through the circulation as to coordinate by chemical trans- port the activities of the body as a whole. Unification by chemical means must today be recognized as a fundamental aspect of all such organisms. In all of them it is true that the nervous system has pride of place as the highest seat of organizing influence, but we know today that even this influence is often, if not always, exerted through properties inherent in chemical molecules. It is indeed most significant for my general theme to realize that when a nerve impulse reaches a tissue the sudden production of a definite chemical substance at the nerve ending may be essential to the re- sponse of that tissue to the impulse. It is a familiar circumstance that when an impulse passes to the heart by way of the vagus nerve fibers the beat is slowed, or, by a stronger beat, arrested. That is, of course, part of the normal control of the heart’s action. Now it has been shown that whenever the heart receives vagus impulses the substance acetylcholin is hberated within the organ. ‘To this fact is added the further fact that, in the absence of the vagus in- fluence, the artificial injection of minute graded doses of acetyl choline so acts upon the heart as to reproduce in every detail the effects of graded stimulation of the nerve. Moreover, evidence is accumulating to show that in the case of other nerves belonging to the same morphological group as the vagus, but supplying other tissues, this same liberation of acetyl choline accompanies activity, and the chemical action of this substance upon such tissues again produces effects identical with those observed when the nerves are stimulated. More may be claimed. The functions of another group of nerves are opposed to those of the vagus group; impulses, for instance, through certain fibers accelerate the heart beat. Again a chemical substance is liberated at the endings of such nerves, and this substance has itself the property of accelerating the heart. We find then that such organs and tissues respond only indirectly to whatever nonspecific physical change may reach the nerve ending. Their direct response is to the influence of particular molecules with an essential structure when these intrude into their chemical machinery. It follows that the effect of a given nerve stimulus may not be confined to the tissue which it first reaches. There may be humeral transmissions of its effect, because the liberated substance enters the lymph and blood. This again may assist the coordination of events in the tissues. From substances produced temporarily and locally and by virtue of their chemical properties translating for the tissues the messages of nerves, we may pass logically to consideration of those active sub- stances which carry chemical messages from organ to organ. Such in the animal body are produced continuously in specialized organs, CHEMICAL ASPECTS OF LIFE—HOPKINS 139 and each has its special seat or seats of action where it finds chemical structures adjusted in some sense or other to its own. I shall be here on familiar ground, for that such agencies exist, and bear the name of hormones, is common knowledge. I propose only to indicate how many and diverse are their functions as revealed by recent research, emphasizing the fact that each one is a definite and relatively simple substance with properties that are primarily chemical and in a derivate sense physiological. Our clear recogni- tion of this, based at first on a couple of instances, began with this century, but our knowledge of their number and nature is still grow- ing rapidly today. We have long known, of course, how essential and profound is the influence of the thyroid gland in maintaining harmonious growth in the body, and in controlling the rate of its metabolism. Three years ago a brilliant investigation revealed the exact molecular struc- ture of the substance—thyroxin—which is directly responsible for these effects. It is a substance of no great complexity. The con- stitution of adrenalin has been longer known and likewise its remark- able influence in maintaining a number of important physiological adjustments. Yet it is again a relatively simple substance. I will merely remind you of secretin, the first of these substances to receive the name of hormone, and of insulin, now so familiar because of its importance in the metabolism of carbohydrates and its consequent value in the treatment of diabetes. The most recent growth of knowledge in this field has dealt with hormones which, in most remarkable relations, coordinate the phenomena of sex. It is the circulation of definite chemical substances produced locally that determines during the growth of the individual, the proper devel- opment of all secondary sexual characters. The properties of other substances secure the due process of individual development from the unfertilized ovum to the end of fetal hfe. When an ovum ripens and is discharged from the ovary a substance, now known as eestrin, is produced in the ovary itself, and so functions as to bring about all those changes in the female body which make secure the fertilization of the ovum. On the discharge of the ovum new tissue, constituting the so-called corpus luteum, arises in its place. This then produces a special hormone which in its turn evokes all those changes in tissues and organs that secure a right destiny for the ovum after it has been fertilized. It is clear that these two hormones do not arise simul- taneously, for they must act in alternation, and it becomes of great interest to know how such succession is secured. The facts here are among the most striking. Just as higher nerve centers in the brain control and coordinate the activities of lower centers, so it would seem do hormones, functioning at, so to speak, a higher level in organiza- tion, coordinate the activities of other hormones. It is a substance 140 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 produced in the anterior portion of the pituitary gland situated at the base of the brain, which by circulating to the ovary controls the succession of its hormonal activities. The cases I have mentioned are far from exhausting the numerous hormonal influences now recognized. For full appreciation of the extent to which chemical substances control and coordinate events in the animal body by virtue of their specific molecular structure, it is well not to separate too widely in thought the functions of hormones from those of vitamins. Together they form a large group of substances of which every one exerts upon physiological events its own indispensable chemical influence. Hormones are produced in the body itself, while vitamins must be supplied in the diet. Such a distinction is, in general, justified. We meet occasionally, however, an animal species able to dispense with an external supply of this or that vitamin. Evidence shows, however, that individuals of that species, unlike most animals, can in the course of their metabolism synthesize for themselves the vitamin in question. The vitamin then becomes a hormone. In practice the distinction may be of great importance, but for an understanding of metabolism the functions of these substances are of more significance than their origin. The present activity of research in the field of vitamins is pro- digious. The output of published papers dealing with original in- vestigations in the field has reached nearly a thousand in a single year. Each of the vitamins at present known is receiving the attention of numerous observers in respect both of its chemical and biological properties, and though many publications deal, of course, with matters of detail, the accumulation of significant facts is growing fast. It is clear that I can cover but little ground in any reference to this wide field of knowledge. Some aspects of its development have been interesting enough. The familiar circumstance that attention was drawn to the existence of one vitamin (B, so called) because populations in the East took to eating milled rice instead of the whole grain; the gradual growth of evidence which links the physiological activities of another vitamin (D) with the influence of solar radiation of the body, and has shown that they are thus related, because rays of definite wave length convert an inactive precurser into the active vitamin, alike when acting on foodstuffs or on the surface of the living body; the fact again that the recent isolation of vitamin C, and the accumulation of evidence for its nature started from the observation that the cortex of the adrenal gland displayed strongly reducing properties; or yet again the proof that a yellow pigment widely distributed among plants, while not CHEMICAL ASPECTS OF LIFE—HOPKINS 141 the vitamin itself, can be converted within the body into vitamin A; these and other aspects of vitamin studies will stand out as interesting chapters in the story of scientific investigation. In this very brief discussion of hormones and vitamins I have so far referred only to their functions as manifested in the animal body. Kindred substances, exerting analogous functions, are, however, of wide and perhaps of quite general biological importance. It is certain that many micro-organisms require a supply of vitaminlike substances for the promotion of growth, and recent research of a very interesting kind has demonstrated in the higher plants the existence of specific substances produced in special cells which stimulate growth in other cells, and so in the plant as a whole. These so- called auxines are essentially hormones. Section B will soon be listening to an account of their chemical nature. It is of particular importance to my present theme and a source of much satisfaction to know that our knowledge of the actual molec- ular structure of hormones and vitamins is growing fast. We have already exact knowledge of the kind in respect to not a few. We are indeed justified in believing that within a few years such knowledge will be extensive enough to allow a wide view of the correlation between molecular structure and physiological activity. Such correlation has long been sought in the case of drugs, and some generalizations have been demonstrated. It should be remembered, however, that until quite lately only the structure of the drug could be considered. With increasing knowledge of the tissue structures pharmacological actions will become much clearer. I cannot refrain from mentioning here a set of relations connected especially with the phenomena of tissue growth which are of par- ticular interest. It will be convenient to introduce some technical chemical considerations in describing them, though I think the relations may be clear without emphasis being placed on such details. The vitamin, which in current usage is labeled “A”, is essential for the general growth of an animal. Recent research has provided much information as to its chemical nature. Its molecule is built up of units which possess what is known to chemists as the “ isoprene struc- ture.” These are condensed in a long carbon chain which is attached to a ring structure of a specific kind. Such a constitution relates it to other biological compounds, in particular to certain vegetable pig- ments, one of which a carotene, so called, is the substance which I have mentioned as being convertible into the vitamin. For the display of an influence upon growth, however, the exact details of the vitamin’s proper structure must be established. Now turning to vitamin D, of which the activity is more specialized, controlling as it does the growth of bone in particular, we have learned that the unit elements in its structure are again isoprene radicals; but instead of forming 142 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 a long chain as in vitamin A they are united into a system of con- densed rings. Similar rings form the basal component of the mole- cules of sterols, substances which are normal constituents of nearly every living cell. It is one of these, inactive itself, which ultra- violet radiation converts into vitamin D. We know that as stated each of these vitamins stimulates growth in tissue cells. Next con- sider another case of growth stimulation, different because patho- logical in nature. As you are doubtless aware, it is well known that long contact with tar induces a cancerous growth of the skin. Very important researches have recently shown that particular constit- uents in the tar are alone concerned in producing this effect. It is being further demonstrated that the power to produce cancer is associated with a special type of molecular structure in these con- stituents. This structure, like that of the sterols, is one of condensed rings, the essential difference being that (in chemical language) the sterol rings are hydrogenated, whereas those in the cancer-producing molecules are not. Hydrogenation indeed destroys the activity of the latter. Recall, however, the ovarian hormone oestrin. Now the molecular structure of oestrin has the essential ring structure of a sterol, but one of the constituent rings is not hydrogenated. In a sense therefore the chemical nature of oestrin links vitamin D with that of cancer-producing substances. Further, it is found that sub- stances with pronounced cancer-producing powers may produce effects in the body like those of oestrin. It is difficult when faced with such relations not to wonder whether the metabolism of sterols, which when normal can produce a substance stimulating physiolog- ical growth, may in very special circumstances be so perverted as to produce within living cells a substance stimulating pathological growth. Such a suggestion must, however, with present knowledge, be very cautiously received. It is wholly without experimental proof. My chief purpose in this reference to this very interesting set of relations is to emphasize once more the significance of chemical structure in the field of biological events. Only the end results of the profound influence which minute amounts of substances with adjusted structure exert upon living cells or tissues can be observed in the intact bodies of man or animals. It is doubtless because of the elaborate and sensitive organization of chemical events in every tissue cell that the effects are proportionally so great. It is an immediate task of biochemistry to explore the mechanism of such activities. It must learn to describe in objective chemical terms precisely how and where such molecules as those of hormones and vitamins intrude into the chemical events of metabolism. It is indeed now beginning this task which is by no means outside the scope of its methods. Efforts of this and of similar kind cannot CHEMICAL ASPECTS OF LIFE—-HOPKINS 143 fail to be associated with a steady increase in knowledge of the whole field of chemical organization in living organisms, and to this increase we look forward with confidence. ‘The promise is there. Present methods can still go far, but I am convinced that progress of the kind is about to gain great impetus from the application of those new methods of research which chemistry is inheriting from physics: X-ray analysis; the current studies of unimolecular surface films and of chemical reactions at surfaces; modern spectroscopy; the quantitative developments of photochemistry; no branch of inquiry stands to gain more from such advances in technique than does biochemistry at its present stage. Especially is this true in the case of the colloidal structure of living systems, of which in this address I have said so little. IV As an experimental science, biochemistry, like classical physiology and much of experimental biology, has obtained, and must continue to obtain, many of its data from studying parts of the organism in isolation, but parts in which dynamic events continue. Though fortunately it has also methods of studying reactions as they occur in intact living cells, intact tissues, and, of course, in the intact ani- mal, it is still entitled to claim that its studies of parts are consistently developing its grasp of the wholes it desires to describe, however remote that grasp may be from finality. Justification for any such claim has been challenged in advance from a certain philosophic standpoint. Not from that of General Smuts, though in his powerful address which signalized our centenary meeting, he, like many philos- ophers today, emphasized the importance of properties which emerge from systems in their integrity, bidding us remember that a part while in the whole is not the same as the part in isolation. He has- tened to admit in a subsequent speech, however, that for experimental biology, as for any other branch of science, it was logical and neces- sary to approach the whole through its parts. Nor again is the claim challenged from the standpoint of such a teacher as A. N. White- head, though in his philosophy of organic mechanism there is no real entity of any kind without internal and multiple relations, and each whole is more than the sum of its parts. I nevertheless find ad hoc statements in his writings which directly encourage the methods of biochemistry. In the teachings of J. S. Haldane, however, the value of such methods have long been directly challenged. Some here will perhaps remember that in his address to section I 25 years ago he described a philosophic standpoint which he has courageously main- tained in many writings since. Dr. Haldane holds that to the en- lightened biologist a living organism does not present a problem for analysis; it is, qua organism, axiomatic. Its essential attributes are 144 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 axiomatic; heredity, for example, is for biology not a problem but an axiom. “The problem of physiology is not to obtain piecemeal physico-explanations of physiological processes” (I quote from the 1885 address), “ but to discover by observation and experiment the relatedness to one another of all the details of structure and activity in each organism as expressions of its nature as one organism.” I cannot pretend adequately to discuss these views here. They have often been discussed by others, not always perhaps with understand- ing. What is true in them is subtle, and I doubt if their author has ever found the right words in which to bring to most others a con- viction of such truth. It is involved in a world outlook. What I think is scientifically faulty in Haldane’s teaching is the a priori element which leads to bias in the face of evidence. The task he sets for the physiologist seems vague to most people, and he forgets that with good judgment a study of parts may lead to an intellectual synthesis of value. In 1885 he wrote: “That a meeting point be- tween biology and physical science may at at some time be found there is no reason for doubting. But we may confidently predict that if that meeting point is found, and one of the two sciences is swallowed up, that one will not be biology.” He now claims, indeed, that biology has accomplished the heavy meal because physics has been compelled to deal no longer with Newtonian entities but, like the biologist, with organisms such as the atom proves to be. Is it not, then, enough for my present purpose to remark on the significance of the fact that not until certain atoms were found spontaneously splitting piecemeal into parts, and others were afterward so split in the laboratory, did we really know anything about the atom as a whole ? At this point, however, I will ask you not to suspect me of claim- ing that all the attributes of living systems or even the more obvious among them are necessarily based upon chemical organization alone. I have already expressed my own belief that this organization will account for one striking characteristic of every living cell—its abil- ity, namely, to maintain a dynamic individuality in diverse environ- ments. Living cells display other attributes even more characteristic of themselves; they grow, multiply, inherit qualities and transmit them. Although to distinguish levels of organization in such systems may be to abstract from reality it is not illogical to believe that such attributes as these are based upon organization at a level which is in some sense higher than the chemical level. The main necessity from the standpoint of biochemistry is then to decide whether nevertheless at its own level, which is certainly definable, the results of experimental studies are self-contained and consistent. CHEMICAL ASPECTS OF LIFE—-HOPKINS 145 This is assuredly true of the data which biochemistry is now acquir- ing. Never during its progress has chemical consistency shown itself to be disturbed by influences of any ultrachemical kind. Moreover, before we assume that there is a level of organization at which chemical controlling agencies must necessarily cease to function, we should respect the intellectual parsimony taught by Occam and be sure of their limitations before we seek for super- chemical entities as organizers. There is no orderly succession of events which would seem less likely to be controlled by the mere chemical properties of a substance than the cell divisions and cell differentiation. which intervene between the fertilized ovum and the finished embryo. Yet it would seem that a transmitted substance, a hormone in essence, may play an unmistakable part in that remarkable drama. It has for some years been known that, at an early stage of development, a group of cells forming the so-called “ organizer ” of Spemann induces the subsequent stages of differentia- tion in other cells. The latest researches seem to show that a cell- free extract of this “ organizer ” may function in its place. The sub- stance concerned is, it would seem, not confined to the “ organizer ” itself, but is widely distributed outside, though not in, the embryo. It presents, nevertheless, a truly remarkable instance of chemical influence. It would be out of place in such a discourse as this to attempt any discussion of the psychophysical problem. However much we may learn about the material systems which, in their integrity, are associated with consciousness, the nature of that association may yet remain a problem. The interest of that problem is insistent and it must be often in our thoughts. Its existence, however, justifies no prejudgments as to the value of any knowledge of a consistent sort which the material systems may yield to experiment. Vv It has become clear, I think, that chemical modes of thought, whatever their limitation, are fated profoundly to affect biological thought. If, however, the biochemist should at any time be inclined to overrate the value of his contributions to biology, or to under- rate the magnitude of problems outside his province, he will do well sometimes to leave the laboratory for the field, or to seek even in the museum a reminder of that infinity of adaptations of which life is capable. He will then not fail to work with a humble mind, however great his faith in the importance of the methods which are his own. It is surely right, however, to claim that in passing from its earlier concern with dead biological products to its present concern 146 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 with active processes within living organisms, biochemistry has become a true branch of progressive biology. It has opened up modes of thought about the physical basis of life which could scarcely be employed at all a generation ago. Such data and such modes of thought as it is now providing are pervasive, and must appear as aspects in all biological thought. Yet these aspects are, of course, only partial. Biology in all its aspects is showing rapid progress, and its bearing on human welfare is more and more evident. Unfortunately, the nature of this new biological progress and its true significance is known to but a small section of the lay public. Few will doubt that popular interest in science is extending, but it is mainly confined to the more romantic aspects of modern astronomy and physics. That biological advances have made less impression is probably due to more than one circumstance, of which the chief, doubtless, is the neglect of biology in our educational system. The startling data of modern astronomy and physics, though of course only when presented in their most superficial aspects, find an easier approach to the uninformed mind than those of the new experimental biology can hope for. ‘The primary concepts involved are para- doxically less familiar. Modern physical science, moreover, has been interpreted to the intelligent public by writers so brilliant that their books have had a great and stimulating influence. Lord Russell once ventured on the statement that in passing from physics to biology one is conscious of a transition from the cosmic to the parochial, because from a cosmic point of view life is &@ very unimportant affair. Those who know that supposed parish well are convinced that it is rather a metropolis entitled to much more attention than it sometimes obtains from authors of guide- books to the universe. It may be small in extent, but is the seat of all the most significant events. In too many current publications, pur- porting to summarize scientific progress, biology is left out or receives but scant reference. Brilliant expositions of all that may be met in the region where modern science touches philosophy have directed thought straight from the implications of modern physics to the nature and structure of the human mind, and even to speculation concerning the mind of the Deity. Yet there are aspects of bio- logical truth already known which are certainly germane to such discussions, and probably necessary for their adequacy. VI It is, however, because of its extreme importance to social prog- ress that public ignorance of biology is especially to be regretted. Sir Henry Dale has remarked that “it is worth while to consider today whether the imposing achievements of physical science have CHEMICAL ASPECTS OF LIFE—HOPKINS 147 not already, in the thought and interests of men at large, as well as in technical and industrial development, overshadowed in our educational and public policy those of biology to an extent which threatens a one-sided development of science itself and of the civi- lization which we hope to see based on science.” Sir Walter Flet- cher, whose death during the past year has deprived the nation of an enlightened adviser, almost startled the public, I think, when he said in a national broadcast that “ we can find safety and progress only in proportion as we bring into our methods of statecraft the guid- ance of biological truth.” That statecraft, in its dignity, should be concerned with biological teaching, was a new idea to many lis- teners. A few years ago the Cambridge philosopher, Dr. C. D. Broad, who is much better acquainted with scientific data than are many philosophers, remarked upon the misfortune involved in the unequal development of science; the high degree of our control over inorganic nature combined with relative ignorance of biology and psychology. At the close of a discussion as to the possibility of continued mental progress in the world, he summed up by saying that the possibility depends on our getting an adequate knowledge and control of life and mind before the combination of ignorance on these subjects with knowledge of physics and chemistry wrecks the whole social system. He closed with the somewhat startling words: “ Which of the runners in this very interesting race will win it is impossible to foretell. But physics and death have a long start over psychology and life!” No one surely will wish for, or expect, a slowing in the pace of the first, but the quickening up in the latter which the last few decades have seen is a matter for high satisfaction. But, to repeat, the need for recognizing biological truth as a necessary guide to individual conduct and no less to state- craft and social policy still needs emphasis today. With frank acceptance of the truth that his own nature is congruent with all those aspects of nature at large which biology studies, combined with intelligent understanding of its teaching, man would escape from innumerable inhibitions due to past history and present ignorance, and equip himself for higher levels of endeavor and success. Inadequate as at first sight it may seem when standing alone in support of so large a thesis, I must here be content to refer briefly to a single example of biological studies bearing upon human wel- fare. I will choose one which stands near to the general theme of my address. I mean the current studies of human and animal nutrition. You are well aware that during the last 20 years—that is, since it adopted the method of controlled experiment—the study of nutrition has shown that the needs of the body are much more complex than was earlier thought, and in particular that substances 111666—35——11 148 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 consumed in almost infinitesimal amounts may, each in its way, be as essential as those which form the bulk of any adequate dietary. This complexity in its demands will, after all, not surprise those who have in mind the complexity of events in the diverse living tissues of the body. My earlier reference to vitamins, which had somewhat different bearings, was, I am sure, not necessary for a reminder of their nutri- tional importance. Owing to abundance of all kinds of advertise- ment vitamins are discussed in the drawing room as well as in the dining room, and also, though not so much, in the nursery, while at present perhaps not enough in the kitchen. Unfortunately, among the uninformed their importance in nutrition is not always viewed with discrimination. Some seem to think nowadays that if the vitamin supply is secured the rest of the dietary may be left to chance, while others suppose that they are things so good that we cannot have too much of them. Needless to say, neither assumption is true. With regard to the second indeed it is desirable, now that vitamin concentrates are on the market and much advertised, to remember that excess of a vitamin may be harmful. In the case of that labeled D at least we have definite evidence of this. Neverthe- less, the claim that every known vitamin has highly important nutritional functions is supported by evidence which continues to grow. It is probable, but perhaps not yet certain, that the human body requires all that are known. The importance of detail is no less in evidence when the demands of the body for a right mineral supply are considered. A proper balance among the salts which are consumed in quantity is here of prime importance, but that certain elements which ordinary foods contain in minute amounts are indispensable in such amounts is becoming sure. To take but a single instance: the necessity of a trace of copper, which exercises somewhere in the body an indis- pensable catalytic influence on metabolism, is as essential in its way as much larger supplies of calcium, magnesium, potassium, or iron. Those in close touch with experimental studies continually receive hints that factors still unknown contribute to normal nutrition, and those who deal with human dietaries from a scientific standpoint know that an ideal diet cannot yet be defined. This reference to nutritional studies is indeed mainly meant to assure you that the great attention they are receiving is fully justified. No one here, TI think, will be impressed with the argument that because the human race has survived till now in complete ignorance of all such details the knowledge being won must have academic interest alone. This line of argument is very old and never right. One thing I am sure may be claimed for the growing enlight- ment concerning human nutrition and the recent recognition of its CHEMICAL ASPECTS OF LIFE—HOPKINS 149 study. It has already produced one line of evidence to show that nurture can assist nature to an extent not freely admitted a few years ago. That is a subject which I wish I could pursue. I cannot myself doubt that various lines of evidence, all of which should be profoundly welcome, are pointing in the same direction. Allow me just one final reference to another field of nutritional studies. Their great economic importance in animal husbandry calls for full recognition. Just now agricultural authorities are becoming acutely aware of the call for a better control of the diseases of ani- mals. Together these involve an immense economic loss to the farm- ers, and therefore to the country. Although, doubtless, its influence should not be exaggerated, faulty nutrition plays no small share in accounting for the incidence of some among these diseases, as re- searches carried out at the Rowett Institute in Aberdeen and else- where are demonstrating. There is much more of such work to be done with great profit. vil In every branch of science the activity of research has greatly increased during recent years. This all will have realized, but only those who are able to survey the situation closely can estimate the extent of that increase. It occurred to me at one time that an ap- praisement of research activities in this country, and especially the organization of State-aided research, might fittingly form a part of my address. The desire to illustrate the progress of my own sub- ject led me away from that project. I gave some time to a survey, however, and came to the conclusion, among others, that from 8 to 10 individuals in the world are now engaged upon scientific investiga- tions for every one so engaged 20 years ago. It must be remembered, of course, that not only has research endowment greatly increased in America and Europe, but that Japan, China, and India have entered the field and are making contributions to science of real importance. It is sure that, whatever the consequences, the increase of scientific knowledge is at this time undergoing a positive acceleration. Apropos, I find difficulty as today’s occupant of this important scientific pulpit in avoiding some reference to impressive words spoken by my predecessor which are still echoed in thought, talk, and print. In his wise and eloquent address at York, Sir Alfred Ewing reminded us with serious emphasis that the command of Nature has been put into man’s hand before he knows how to command himself. Of the dangers involved in that indictment he warned us; and we should remember that General Smuts also sounded the same note of warning in London. Of science itself it is, of course, no indictment. It may be thought of rather as a warning signal to be placed on her road: “ Dangerous 150 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 hill ahead”, perhaps, or “Turn right”; not, however, “Go slow”, for that advice science cannot follow. ‘The indictment is of man- kind. Recognition of the truth it contains cannot be absent from the minds of those whose labors are daily increasing mankind’s command of Nature; but it is due to them that the truth should be viewed in proper perspective. It is, after all, war, to which science has added terrors, and the fear of war, which alone give it real urgency; an urgency which must, of course, be felt in these days when some nations at least are showing the spirit of selfish and dangerous nationalism. I may be wrong, but it seems to me that, war apart, the gifts of sci- ence and invention have done little to increase opportunities for the display of the more serious of man’s irrational impulses. The worst they do, perhaps, is to give to clever and predatory souls that keep within the law the whole world for their depredations, instead of a parish or a country as of yore. But Sir Alfred Ewing told us of “ the disillusion with which, now standing aside, he watches the sweeping pageant of discovery and invention in which he used to make unbounded delight.” I wish that one to whom applied science and this country owe so much might have been spared such disillusion, for I suspect it gives him pain. I wonder whether, if he could have added to an “engineer’s out- look” the outlook of a biologist, the disillusion would still be there. As one just now advocating the claims of biology, I would much like to know. It is sure, however, that the gifts of the engineer to humanity at large are immence enough to outweigh the assistance he may have given to the forces of destruction. It may be claimed for biological science, in spite of vague refer- ences to bacterial warfare and the like, that it is not of its nature to aid destruction. What it may do toward making man as a whole more worthy of his inheritance has yet to be fully recognized. On this point I have said much. Of its service to his physical better- ment you will have no doubts. I have made but the bare reference in this address to the support that biological research gives to the art of medicine. I had thought to say much more of this, but found that if I said enough I could say nothing else. There are two other great questions so much to the front just now that they tempt a final reference. I mean, of course, the paradox of poverty amidst plenty and the replacement of human labor by ma- chinery. Applied science should take no blame for the former, but indeed claim credit unfairly lost. It is not within my capacity to say anything of value about the paradox and its cure; but I confess that I see more present danger in the case of “ Money versus Man ” than danger present or future in that of the “ Machine versus Man”! With regard to the latter it is surely right that those in touch with science should insist that the replacement of human labor will con- CHEMICAL ASPECTS OF LIFE——-HOPKINS 151 tinue. Those who doubt this cannot realize the meaning of that posi- tive acceleration in science, pure and applied, which now continues. No one can say what kind of equilibrium the distribution of leisure is fated to reach. In any case an optimistic view as to the probable effects of its increase may be justified. It need not involve a revolutionary change if there is real planning for the future. Lord Melchett was surely right when some time ago he urged on the upper House that present thought should be given to that future; but I think few men of affairs seriously believe what is yet probable, that the replacement we are thinking of will impose a new structure upon society. This may well differ in some essentials from any of those alternative social forms of which the very names now raise antagonisms. I confess that if civilization escapes its other perils I should fear little the final reign of the machine. We should not altogether forget the difference in use which can be made of real and ample leisure compared with that possible for very brief leisure associated with fatigue; nor the difference between compulsory toil and spontaneous work. We have to picture, moreover, the reactions of a community which, save for a minority, has shown itself during recent years to be educable. I do not think it fanciful to believe that our highly efficient national broadcasting service, with the increased opportunities which the coming of short wave length transmission may provide, might well take charge of the systematic education of adolescents after the personal influence of the schoolmaster has pre- pared them to profit by it. It would not be a technical education but an education for leisure. Listening to organized courses of instruc- tion might at first be for the few; but ultimately might become habitual in the community which it would specifically benefit. In parenthesis allow me a brief further reference to “ planning.” The word is much to the front just now, chiefly in relation with cur- rent enterprises. But there may be planning for more fundamental developments; for future adjustment to social reconstructions. In such planning the trained scientific mind must play its part. Its vision of the future may be very limited, but in respect of material progress and its probable consequences science (I include all branches of knowledge to which the name applies) has at least better data for prophecy than other forms of knowledge. It was long ago written, “ Wisdom and knowledge shall be stability of Thy times.” Though statesmen may have wisdom adequate for the immediate and urgent problems with which it is their fate to deal, there should yet be a reservoir of synthesized and clarified knowl- edge on which they can draw. The technique which brings govern- ments in contact with scientific knowledge in particular, though greatly improved of late, is still imperfect. In any case the politician is perforce concerned with the present rather than the future. I 152 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 have recently read Bacon’s New Atlantis afresh and have been thinking about his Solomon’s House. We know that the rules for the functioning of that House were mistaken because the philosopher drew them up when in the mood of a Lord Chancellor; but insofar as the philosopher visualized therein an organization of the best intellects bent on gathering knowledge for future practical services, his idea wasa great one. When civilization is in danger and society in transi- tion might there not be a House recruited from the best intellects in the country with functions similar (mutatis mutandis) to those of Bacon’s fancy? A House devoid of politics, concerned rather with synthesiz- ing existing knowledge, with a sustained appraisement of the progress of knowledge, and continuous concern with its bearing upon social readjustments. It is not to be pictured as composed of scientific authorities alone. It would be rather an intellectual exchange where thought would go ahead of immediate problems. I believe, perhaps foolishly, that given time I might convince you that the functions of such a House, in such days as ours, might well be real. Here I must leave them to your fancy, well aware that in the minds of many I may by this bare suggestion lose all reputation as a realist! I will now hasten to my final words. Most of us have had a tendency in the past to fear the gift of leisure to the majority. To believe that it may be a great social benefit requires some mental adjustment, and a belief in the educability of the average man or woman. But if the political aspirations of the nations should grow sane, and the artificial economic problems of the world be solved, the com- bined and assured gifts of health, plenty, and leisure may prove to be the final justification of applied science. In acommunity advantaged by these each individual will be free to develop his own innate powers, and, becoming more of an individual, will be less moved by those herd instincts which are always the major danger to the world. You may feel that throughout this address I have dwelt exclusively on the material benefits of science to the neglect of its cultural value. I would lke to correct this in a single closing sentence. I believe that for those who cultivate it in a right and humble spirit, science is one of the humanities; no less. COMMERCIAL EXTRACTION OF BROMINE FROM SEA WATER* By Leroy C. STEWART The Dow Chemical Company, Midland, Mich. [With 7 plates] In 1924 the production of free and chemically combined bromine in this country amounted to approximately 2 million pounds. In 1931 this quantity had risen to about 9 million pounds, all of which was being produced from natural brines and from bitterns resulting from evaporation of sea water. This remarkable increase in con- sumption of bromine was due largely to the use of ethylene di- bromide in conjunction with tetraethyllead in the treatment of gasoline motor fuel. A number of years ago it became evident that the demand for bromine was becoming so great that its ordinary sources were inade- quate and that new ones would have to be employed. It was logical that sea water should be considered for this purpose, in spite of the fact that its bromine content is less than 70 parts per million, since the enormous quantities of it which are available would insure an inexhaustible source of raw material. It was up to the chemist and engineer, however, to develop a practical and economical method of extracting this desirable halogen element. The Ethyl Gasoline Corporation was one of the pioneers along this line. In 1924 they operated a small-scale plant with sea water as its source of bromine and produced tribromoaniline which can be used with tetraethyllead in the treatment of gasoline. Some months later, the same organization operated the process on board a boat, the 8. S. Hthyl (4).2. Their method involved the addition of aniline to chlorinated sea water to form tribromoaniline according to the reaction: 3NaBr a5 3Cl, Se C;H;NH, —_—> @2be Br, NE. ah 3NaCl aF 3HCl A number of years ago the Dow Chemical Company likewise undertook the problem of extracting bromine from sea water, but 1 Reprinted by permission from Industrial and Engineering Chemistry, vol. 26, p. 361, April 1934. 2 Numbers in parentheses refer to list of literature cited at end of paper. 153 154 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 proposed to obtain it in the pure, elemental state by a process some- what similar to that in use on natural brines at their plant in Mid- land, Mich. It was recognized that modifications and refinements would have to be made in the old procedure, but the basic principle was considered practical and economically sound. ‘This process con- sists essentially of (a) oxidizing a natural bromide-containing brine with chlorine to liberate the bromine, (0) blowing the free bromine out of solution with air, and(c) absorbing the bromine from the air with an alkali carbonate solution from which it subsequently can be recovered in a commercially desirable form. Through many years of experience and effort, the Dow process has been developed to the point where it is possible to recover, con- sistently, 95 percent of the bromine content of the natural brines. The latter contain approximately 25 percent total solids, consisting chiefly of the chlorides of sodium, calcium, and magnesium, together with approximately 1,300 p. p. m. bromine. Sea water, however, contains about 3.5 percent total solids, and only 65 to 70 p. p. m. bromine. This is approximately the same bromine content as that of the waste effluent from the commercial process just mentioned. Consequently, when laboratory work was started on the problem of removing bromine from sea water, it is not surprising that at first a low efficiency was obtained. RESEARCH LABORATORY DEVELOPMENTS It was realized that an addition of acid as well as chlorine would be necessary in order to obtain a satisfactory yield of bromine from sea water on account of its alkalinity, as indicated by its pH of 7.2. 0 4 6 l@ 16 20 24 26 32 36 40 44 48 52 56 60 cuBIC CENTIMETERS Y Ha FIG. / EFFECT OF ADDITION OF AC/D ON pH OF SEA WATER Otherwise, when the solution was chlorinated, neutralization would have been effected at the expense of the liberated bromine. At the same time there would have been a corresponding formation of BROMINE FROM SEA WATER—STEWART 155 oxidized bromine products from which bromine could not have been liberated easily again by chlorine. However, it was found that even in carefully neutralized sea water, a satisfactory yield of bromine was not obtained. An ex- planation of this appeared to be that in the exceptionally dilute solution the liberated bromine hydrolyzed to form bromic and hydrobromic acids according to the equation: 3Br.+3H.0 —- HBrO,+5HBr This being the case, such reaction would have continued until a sufficient concentration of hydrogen ions was obtained to suppress the hydrolysis. In the production of bromine from Michigan brines, some hy- drolysis and reabsorption of the halogen, with the attendant forma- tion of acid, had been encountered. Because of the comparatively smaller volume handled in the case of the natural brine, it was Hf VALUE FIG. 2 LFFEGCT OF pt ON PERCENTAGE OF BROMINE LIBERATED IN SEA WATER feasible to permit such acidification by hydrolysis to take place and, still to make a satisfactory recovery of the bromine. However, in the case of the enormous quantity of liquid involved with sea water as the source of bromine, such acidification by hydrolysis would be uneconomical. Careful laboratory research, involving po- tentiometric titration of natural sea water, showed that reabsorp- tion of free bromine by hydrolysis ceased if the hydrogen-ion con- centration were increased to a pH of 3 or 4 by the addition of acid from an outside source. This indicated, therefore, that in order to liberate bromine in sea water completely and efficiently, it would be necessary first to add sufficient acid to give a pH of approximately 3.5. This would require the use of approximately 0.27 pound of 96 percent sulphuric acid per ton of sea water. In operation of the tribromoaniline process, already mentioned, it had also been found that it was desirable to add acid to the raw sea water before adding the chlorine, but a greater proportion was employed. 156 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 Figure 1 shows the variation in pH of raw sea water as affected by the addition of acid. Figure 2 shows the effect of variation of pH on the percentage of total bromine that can be liberated from the sea water by chlorine oxidation. Figure 3 indicates the effect of variation of pH of sea water on the chemical equivalents of chlo- rine required to liberate one equivalent of bromine. Figure 3 shows that, at a pH of 3.5 or less, the theoretical mole of chlorine was required per mole of bromine which was liberated. With the knowledge at hand of the definite proportion of acid which would have to be added to sea water in order to promote a highly efficient process, the next research problem which arose was that of developing a means of immediately and continuously indi- cating the progress of oxidation in the chlorination step, so that the degree of liberation of bromine could be ascertained at any time. /0 si selec sll e-Lo ea cae a el Dhl al Bes i Se a VRRP eae eee a ee ° M SEGRE Rnee ib A | a FS 5) 205 ak | RT FERRE =] i = / Pe aoe | S| S| “ CUED eee ees pil SAD t FIG. 3 EFFECT OF pH ON CHLORINE REQUIRED TO LIBERATE BROMINE IN SEA WATER With the use of the ocean as a source of bromine, such enormous quantities of water were involved that, without some such control method, together with a method of continuously recording acidity, large losses of chlorine and acid would be sure to occur before the operator would realize what was happening. A method was finally developed which answered all requirements. The new method of oxidation control depended on the fact that for every type of bromide-containing solution there is a characteristic range of oxidation potential values. This range depends on the ini- tial concentration of bromine ions and also upon the collective effect of other ions present. It was found that, in acidified sea water, the first traces of free bromine in a solution that was being tested caused an immediate increase in oxidation potential. This rise was meas- BROMINE FROM SEA WATER—STEWART 157 ured by the difference in voltage between a saturated calomel elec- trode and a platinum electrode. Figure 4 shows the relationship between the oxidation potential, expressed in volts, and the percent- age of bromine liberated in sea water which contained about 3.5 percent total solids in solution and about 60 to 70 parts per million bromine, and which had been acidified to a pH of 3 to 4. The char- acteristic potential under these conditions ranged between 0.88 and 0.97 volt. The methods of extracting bromine from sea water, in- volving the control of acidification and oxidation, are protected by patents (3). maa 2 P| | aS ee ee i 1.0 rag ote ree SFA. WATER hic : 3.5 PER CENT TOTAL SOLIDS = Re 60-70 PPM BROMINE fei WG 6 O 10 20 30 40 50 60 70 80 90 100 I10 120 130 140 PERGENTAGE BROMINE LIBERATED FRG Ad peace race OF BROWNE LIBERATED Il) SEA WATER PERCENTAGE OF BROMINE LIBERATED IN SEA WATER After obtaining a clear understanding of the factors which made for the most efficient liberation of bromine from sea water and devel- opment of satisfactory control methods, the laboratory and semiplant work on the process progressed much more rapidly. This work es- tablished the fact that air, blown countercurrent through a 70 parts per million bromine solution, would remove the halogen sufficiently to leave a concentration as low as 5 parts per million. It was also found that soda ash solution would effectively remove the very low concentration of bromine from the air. In these experiments, per- formed at Midland, Mich., synthetic sea water was used at first, and this was followed by tests made on tank-car shipments of true sea water. The chief result of the small-scale work was the demonstra- tion that more than 50 percent of the bromine in the real sea water could be extracted and actually collected as the pure liquid. The indicated cost of operating the process seemed satisfactorily low. 158 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 SELECTION OF PROCESS AND PLANT SITE Considerable other research work was done before the final process was selected. Other natural waters, as well as sea water, were inves- tigated as sources of bromine, and improved methods were devised for their use. More economical methods in conjunction with the liberation of bromine were studied, including the use of hme or metallic iron to remove bicarbonates from solution and thus to save acid. Many different processes for removing bromine from very dilute solutions were tried extensively in the laboratory, some on semiplant scale. These included precipitation (1), extraction, and vaporization of the bromine as well as its absorption and adsorption in various agents, particularly in charcoal (2). While some showed fair success, the technic of blowing the bromine from solutions as dilute as the tailings from previous practice was improved and devel- oped to a sound process as already described. Various methods were devised for recovering the bromine from the blowing-out air by both physical and chemical means, including immediate reaction of the bromine with ethylene. It is possible that some such improvements may be employed in the next few years. Finally, the commercial phases of correlating this industry with others were given careful study, and publication of the more interesting and important possi- bilities may be expected. A comparison of the two general methods of obtaining bromine from sea water indicated that the direct extraction process possessed several economic advantages over the tribromoaniline method: 1. The direct process requires theoretically only 1 mole of chlorine for each mole of bromine which is liberated, whereas the other scheme requires 2 moles of chlorine per mole of bromine. 2. Smaller quantities of sulphuric acid are required by the direct process than by the other method. 8. Aniline is a relatively expensive raw material and is at a further economic disadvantage as a carrier of bromine for gasoline treatment when it is con- sidered that tribromoaniline contains only 73 percent bromine, whereas ethylene dibromide is 85 percent bromine. At this point in the history of the development it was decided to build and operate a pilot plant for extracting bromine from sea water by the Dow Chemical Company’s process. The site for this unit was selected after considerable careful investigation, as it was proposed to build a commercial plant in the same location if the results of this venture were satisfactory. The chief requisites for such a site were: 1. The sea water at the point selected should not be diluted by fresh-water streams. BROMINE FROM SEA WATER—STEWART 159 2. The location should be such that it would be easy to get rid of the sea water from which the bromine had been extracted, without diluting the water entering the process. 3. There should be no appreciable quantities of industrial waste present in the water entering the process. A thorough study was made of the eastern and southern coast lines of this country. In this connection information learned from United States Coast and Geodetic Survey, to the effect that the water of all streams entering the Atlantic Ocean flows southward, was of con- siderable assistance. Many samples of sea water were analyzed, and, except where dilution with fresh water was indicated by a study of the location from which the sample was taken, the bromine content was found to be 67 parts per million. Before construction of the com- mercial plant, about 20 samples were taken during a boat trip from New Orleans to Havana and then to New York. ‘The same bromine content of the deep-sea water was found throughout the entire distance. The various factors involved in the selection of the plant site all indicated that it should be located on the north shore of a river, close to the point where it entered the Atlantic Ocean, and that there should be no large river entering the ocean for a number of miles to the north of such a location. The long narrow peninsula in North Caro- lina at the mouth of the Cape Fear River, which separates the latter from the ocean, appeared to answer all the above requirements. Con- sequently, a large tract of land was acquired near the southern end of this peninsula, and in 1931 a pilot plant was constructed and oper- ated to extract 500 pounds of bromine per day from sea water. The bromine was absorbed in soda ash solution to form a bromide-bromate liquor frora which bromine could have been liberated by acidification. Operation of this small unit for 6 months furnished valuable experi- ence which aided in the design of the commercial plant which was to follow. CONSTRUCTION DATA ON COMMERCIAL PLANT About the middle of July 1933 the Ethyl-Dow Chemical Company was Incorporated and the decision was made to construct a plant hav- ing a capacity to extract about 15,000 pounds of bromine per day from sea water and to manufacture it into somewhat more than 16,000 pounds of ethylene dibromide per day. Within a period of 5 months the plans were drawn, materials assembled, and the plant built and put into operation. The design and construction was executed by the Dow Chemical Company organization with the exception of some of the common building operations which were let on contract. 160 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 It is believed that this is an achievement in chemical engineering which is worthy of note, as the following facts relative to the con- struction of the plant will testify: Clearing ‘of ‘groundWstarted 52 ee ee ee ee July 27, 1933 Land) ) Cleared saeresgent tei. woe. ce ke slau ee ead 90 Ground broken sf Or ilies tao UNL any ee eee Aug. 15, 1933 Production of ethylene dibromide commenced__________________ Jan. 10, 1934 Wood pilesvdrivent(S0) feet lomo es eee ee ee 1,800 Sheet steel piling (36-50 feet long), tons______________________. 750 HXcavatlonMewupie yards Less ees eee Se hee ee 125,000 Dred eine iC) Vas ae re ee ee el 100,000 Conerete CUDICRY ATS fe 8 ere Ee ee 8,892 ReenLorcin'siSteel tonsa sas = es yee ene ee ee 425 SELUI CURA STCS] tO Tse ae es 2 ET NAPUS yyw) ees See RO De SEAS 350 Hlectricrconduit, miles 2 eee ee ee eS ee 9.5 HMICCtrichwirin gs Dail s hee Saye os ek es 38 N29 3K} ez) STU rls lee argh ree es ONS Sr LENCO EP CLL pees, Cree SPE 3,540,764 Maximum number men employed at one time, approximate_____- 1,500 ANT OCS. duane ey Worl Ore perth ys 90,000 I aa haa eh ay ee ee ae ae oe a er TON YJ 150 Kirsh working drawing completed see Aug. 14, 1933 Last workinesrawine completed ss 2st eee Nov. 2, 19383 Number of principal drawings (24 by 86 inches) —~--_-__________. 265 The construction facts become even more impressive when it is realized that the nearest railroad shipping point is at Wilmington, approximately 20 miles away. Consequently the large quantities of materials which were involved had to be trucked that distance to the construction site. In order that the work might proceed rapidly, a considerable number of engineers and superintendents were required. These were accommodated in a nearby 50-room beach hotel which was leased and operated by the Ethyl-Dow Chemical Com- pany. Shortly before the construction work was completed, a wharf was built and a channel was dredged out to the navigable part of the Cape Fear River so that boat transportaion could be used for deliver- ing operating supplies to the plant. The boat that has been acquired for this purpose is 116 feet long and is propelled by a 100 horsepower Diesel engine. It has a capacity of about 140 tons. One of its chief cargoes is sulphuric acid which is carried in special tanks installed below deck. The trip from the plant to the dock in Wilmington requires from 2 to 4 hours. Figure 5 is a flow sheet showing the scheme of operations. Figure 6 shows the general layout of the plant. OCEAN WATER INTAKE, CANAL, AND POND The design and construction of the ocean water intake offered an opportunity for ingenuity and engineering foresight. No plans or BROMINE FROM SEA WATER—STEWART 161 descriptions of a structure such as it was desired to construct were available. Experience obtained in putting down an intake pipe for the pilot plant indicated that a single row of piling would not sur- vive the pounding of the ocean waves. It had been found, however, ea Worer vay Blowing- Out Seo Worer Ef¥¢luent ir -in Towers Yo Alver Soda Ash absarptian JOwers Storage Tonks Wo 8r= No Br Oy Solu tien fthyl Alcohol Sulphuric Acid £+hy lene Wbramicge Soli Suloho#te> fthylene furnace Reactor end eee a aii Finishing Still Finished | 4t4ylere Dibramide FIG. § FLOW SHEET Sthylene Dibromide trom Bromine fatracted tram Sea Worer Ficurn 5.—Manufacture of ethylene dibromide from bromine extracted from sea water. that a row of piling on each side of the pipe remained rigid when tied together with a large number of crosspieces. In planning the intake of the new plant, it was decided, therefore, to cut a channel out into the ocean for a short distance and to protect it with a rigid wall on each side. The walls were each to consist of two parallel rows of piling tied together at suitable intervals. ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 162 Neves 2-O DM IEW VAT oh ‘apIMOAqIp eueTAqIO OJUL FL SULANJOVJNUBI PUB JdJVM Bos WOIJ ouTMOIq SuljoVI}xe IOJ yUBd Jo ynoAVI—'g auaADIY — ee SYIMOL NO/LdyOsSEv | ONV 1NO ONIMOTE S| 0% 0% oo Zee FIVYOLS ay i Y ‘9q7@ HSV VvdOS. INV Td zomorgia OOO => frites) (ma = ae a a JISNOH YIMOd INV. LNVTd INITAHLF f Oa Ala, We de Efe) t7 2) | | | | =, —— BROMINE FROM SEA WATER—STEWART 163 In constructing the intake walls, 50-foot lengths of interlocking sheet steel piling were used. These were driven to a depth of about 42 feet below mean low-tide level. The parallel rows of piling in each wall were joined together at every tenth member by a partition of similar piles at right angles to the direction of the wall. Con- sequently, when completed, each wall of the intake consisted of a series of interlocked cells 21 feet long and 15 feet wide. These were built, one at a time, beginning at the shore end and were filled with sand that was dug from the channel between them. Altogether the intake (pl. 1, fig. 2) is about 200 feet long. It extends approximately 30 feet out into the ocean at low tide and about the same distance onto the land at high tide. The channel between the walls is 15 feet wide and the depth is 9 feet below mean low-tide level. The sea water flows through the intake into a settling basin which is 112 feet long, 76 feet wide, and 12 feet deep. The walls in this case were formed from a single row of 40-foot steel piles. These were left with about 14 feet exposed above mean low-tide level and are about level with the surrounding ground. The walls of the settling basin had to be supported from the outside in order to keep them from collapsing toward the inside. This was accomplished by bolting 24-inch I-beams to every eighth piece of piling and extending 2.5-inch steel rods about 30 feet out from each I-beam to anchor into timber piling which served as “dead men ” to absorb the thrust of the dirt against the piling wall. In putting down the steel piles, considerable difficulty was ex- perienced in driving the first few members. When these were in place, it was found expedient to use water jets to aid in sinking the subsequent units. A 0.75-inch nozzle was carried down on each side of the piles, and, by forcing the water through the nozzles at 100 pounds per square inch pressure, it was possible to drive them a considerable distance merely by raising and dropping them. When the power required to raise a pile became too great for the derrick, the jetting was continued and a hammer appled to the top of the pile until the latter was driven to the desired depth. In order to keep the piles of the intake walls in perfect alignment so that there would be no difficulty in tying-in the cross partitions, a frame was constructed which was suspended in the air and which kept the piles perfectly straight in their desired location. Four concrete compartments were built along the end of the set- tling basin opposite the intake. At the present time three of these are closed off with plank bulkheads to keep out floating debris. The fourth compartment has installed at its entrance a 120-inch Link- 111666—35——12 164 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 Belt traveling screen which removes floating sticks and other foreign matter. The pump house, adjacent to these concrete wells, contains two 30-inch centrifugal pumps. One of these has a capacity of about 26,000 gallons per minute, and the other can deliver approximately 32,000 gallons per minute. They are operated by 300-horsepower synchronous motors. The intake pipe for the pumps extends 9 feet below the water level at low tide, whereas the screens operate to practically the full depth of the compartment, which is 3 feet lower. In starting the pumps a Nash Hytor vacuum pump is employed to prime them. Three to five minutes are usually required to accom- plish priming by this method. An interior view of the pump house appears in plate 2, figure 1. Each of the centrifugal pumps is connected to a separate 42-inch steel pipe line which carries the water under a road into a 72-inch steel pipe. The latter conducts the water up over a concrete dam (pl. 2, fig. 2) into a canal and pond. The purpose of the dam is to prevent the emptying of the canal and pond back into the ocean when the pumps are not in operation. The top of the dam is at a level of 23 feet above mean low tide. The canal is about 6 feet deep and extends about 4,000 feet across the peninsula to the plant, which is located close to the shore of the Cape Fear River. Approximately 2,200 feet of the canal are diked off from a pond through which the sea water is bypassed during the summer months. With some 900,000 square feet of exposed surface, the pond permits an increase in temperature during warm weather. This increases the efficiency of the process during several months of the year. After the water has been pumped over the dam and into the canal or pond, it flows to the extraction plant with a loss in head of only about 3 inches. A view of the canal and pond is shown in plate 3, figure 1. The pilot plant is visible near the far left-hand corner of the pond. BROMINE EXTRACTION The extraction of bromine from sea water takes place in two identical units which are located at the exit of the canal. A dia- eram of one of them is shown in figure 7. Each unit consists chiefly of a blowing-out tower in which a current of air removes the bromine from acidified and oxidized sea water, and an adjacent absorption tower in which the bromine is extracted from the air by means of a soda-ash solution. The towers are built of brick and have concrete floors and foundations. The foundations of each unit cover an area 197 by 84 feet. Wood piles 30 feet long were driven in the ground beneath the foundations to avoid any possibility of their settling. BROMINE FROM SEA WATER—STEWART 165 The original ground where these structures are located was exca- vated to a depth of 9 feet or to a level which is about 5 feet above the river at low tide. This was done to minimize the height that the sea water would have to be pumped to the top of the blowing-out towers. A horizontal steel flume, which is semicircular in cross-section and 10 feet in diameter, extends between the two extraction units and con- nects with the canal which brings in the sea water. Because the bases of the towers and the area between them are below the canal level, the flume is carried on steel supports so that it is at the same level as the canal (pl. 3, fig. 2). The absorption towers are located at the end of the flume which is nearest the canal. Hence, the water passes by them on its way to centrifugal pumps which elevate it to the tops of the blowing-out columns. Before entering the pumps, however, the water flows through a traveling screen at the end of the flume. This filters out any leaves or debris which may fall into the water after it enters the canal or pond. AIR EXIT tf CHLORINE INLET —> = ACID INLET —~ == EFFLUENT SEA WATER TO CAPE FEAR RIVER INLET SEA WATER FROM ATLANTIC OCEAN Figure 7.—Diagram of bromine extraction unit. In each extraction unit the sea water is pumped to the top of the blowing-out tower through a vertical 42-inch rubber-lined pipe. Near the bottom of this, a 10 percent sulphuric acid solution is introduced into the water through a group of small rubber-lined pipes. A short distance higher the chlorine is introduced through similar rubber- lined pipes. At the top of the blowing-out tower the water passes through a series of large and small distributor boxes and pipes so that it eventually is divided up into about 3,200 small streams. These flow down through the tower, which is partitioned off into narrow cham- bers extending the full width of the structure. These chambers are filled with wood packing and are operated in parallel. A stream of air is sucked up through the tower countercurrent to the sea water. The bromine that has been liberated by the chlorine is thus blown out of the sea water, and the latter passes out of the bottom of the tower 166 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 through exit flumes to the river and thence into the ocean about 12 miles south of the intake. Plate 4, figure 1, shows a view of the exit flume. The treatment of the sea water on its way to the blowing-out towers is regulated from the nearby control laboratory. Meters on a wall of the laboratory continuously show both the pH of the acidified sea water and its oxidation potential with respect to bromine liberation. Valves in the sulphuric acid and chlorine lines which lead to the 49-inch vertical mixing pipes are operated by hand from the control laboratory. At a later date it is probable that the control of these valves will be made automatic. Signal lights above the meters also indicate whether the condition of the treated sea water is correct for the blowing-out towers. The chlorine which is used in oxidizing the sea water is obtained from cylinders having a capacity of 1 ton. A group of 16 of these is placed in each of 2 wooden compartments. ‘These are kept at a temperature of not less than 70° F. The cylinders are connected to the chlorine line and their contents, in liquid form, flow to the chlorine vaporizer. This is a steam-jacketed iron pipe and is located adjacent to the control laboratory. The sulphuric acid is delivered to the plant in the concentrated form, but it is diluted to a 10 percent solution before it is added to the sea water. This dilution is accomplished in two rubber-lined tanks, 16 feet in diameter and 10 feet high. These are located adjacent to the contro] laboratory. In each extraction unit the air from the blowing-out tower is drawn through its adjacent absorption tower by three fans which are located on a concrete platform at the end of the unit. The air, just before entering the fans, passes through a small wood-filled chamber which catches any spray of soda ash solution that might otherwise be carried out of the system. In the absorption tower the bromine is removed from the air by a soda ash solution to form a dissolved mixture of sodium bromide and bromate according to the formula: 3Na.CO,+3Br, —>» 5NaBr+NaBrO,+3CO, The absorption towers are built on reenforced concrete arches which elevate their floors so as to permit gravity flow of the dissolving liquor into tanks which are located at their bases. This construction also makes possible the detection of any leakage which might take place in the tower bases at any future time. Each absorption tower is divided into nine chambers which are connected in series so that the air, passing in at the end adjacent to the blowing-out tower, follows in succession through these absorbing BROMINE FROM SEA WATER—STEWART 167 chambers and out through the suction fans. Soda ash solution is circulated continuously in each chamber. This is done by pumping it from a tank at the bottom and spraying it in at the top through 36 nozzles, from which it falls by gravity and drains again into the tank. At proper intervals the strong bromide-bromate solution formed in the absorption chamber adjacent to the blowing-out tower is pumped to a storage tank. The charges of partially brominated soda ash liquor in the other members of the series are then pumped forward, in turn, to the next tank nearer the one which has just been emptied to storage. When the tank farthest from the blowing-out tower has been emptied, it is charged with a fresh solution of soda ash. Plate 4, figure 2, shows the south end of the bromine extraction plant. Plate 5, figure 1, is a view looking down on the absorption liquor tanks, and plate 5, figure 2, shows the battery of pumps which circu- late the soda ash solution. The inlet flume may be seen overhead. After the bromine from the sea water has been collected in the form of a solution of sodium bromide and bromate, the remainder of the process is performed according to methods which have been pre- viously in use in the industry. The bromide-bromate liquor is treated with sulfuric acid to liberate the bromine. The free bromine vapors are then steamed out of the acidified solution and are condensed into pure liquid bromine. Plate 6, figure 1, shows the plant in which the bromine is finally obtained in liquid form. The two bromide-bromate liquor storage tanks are seen at the side of the building and the hori- zontal sulfuric acid storage tanks are in front of it. The bromine is used in the manufacture of ethylene dibromide, which is also made in the building shown in plate 6, figure 1. Ethyl- ene is made by passing ethyl alcohol vapor over heated kaolin cata- lyst to form ethylene gas, which is in turn brominated according to the standard method to form pure ethylene dibromide. Plate 6, fig- ure 2, shows the ethylene plant and powerhouse, which are both in the same building. The battery of valves for controlling the ethylene production is shown in plate 7, figure 1. A consignment of finished product on the shipping platform of the ethylene dibromide plant is shown in plate 7, figure 2. The powerhouse employs hand-fired boilers and makes steam only for heating and evaporating purposes. Its capacity is about 15,000 pounds of steam per hour at a pressure of 150 pounds per square inch. Operating electric power is purchased from the Tidewater Power Co. It is delivered to the plant at 33,000 volts, where it is stepped down to 2,300 volts in two transformer banks. The entire plant is functioning as anticipated and is removing about 15,000 pounds of bromine per day from sea water. This is 168 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 being converted into ethylene dibromide at an efficiency somewhat over 90 percent. The direct recovery of minerals for industrial use from sea water has long held the attention of chemists, and it is believed that the plant which has been described is the first to accomplish this achieve- ment on a commercial scale of operation. The extraction of gold from sea water, in which it is present to the extent of but a few parts per billion, has always been the investigator’s most fascinating goal, but no success along this line has been reported thus far. Now that the recovery of bromine, which is present to the extent of less than 70 parts per million, has been successfully executed, it does not seem beyond reason to expect the chemist of the next decade to extract gold from sea water commercially. LITERATURE CITED (1) Grebe, J. J., United States Patent 1891888 (Dec. 20, 1932). (2) Grebe, J. J., and Boundy, R. H., Ibid., 1885255 (Nov. 1, 1982). (3) Grebe, J. J., Boundy, R. H., and Chamberlain, L. C., [bid., 1917762 (July 11, 1933) ; Grebe and Boundy, Ibid., 1944738 (Jan. 23, 1984). (4) Stine, C. M. A., Ind. Eng. Chem., vol. 21, pp. 48442, 1929. Smithsonian Report, 1934.—Stewart PEATE 1 1. PLANT FOR EXTRACTING BROMINE FROM SEA WATER IT INTO ETHYLENE DIBROMIDE. (Compare figure 6.) 2. SEA-WATER INTAKE. AND MANUFACTURING Smithsonian Report, 1934.—Stewart PLATE 2 1. INTERIOR OF PUMP HOUSE AT SEA-WATER INTAKE. 2. SEA WATER BEING PUMPED OVER DAM AT RATE OF 58,000 GALLONS PER MINUTE. Smithsonian Report, 1934.—Stewart PLATE 3 1. CANAL AND POND FOR PASSING SEA WATER TO BROMINE EXTRACTION PLANT. 2. FLUME FOR CONDUCTING SEA WATER TO BLOWING-OUT TOWERS. Smithsonian Report, 1934.—Stewart PLATE 4 1. EFFLUENT SEA WATER PASSING FROM BLOWING-OUT TOWERS TO RIVER. CS Sea + 2. SOUTH END OF BROMINE EXTRACTION UNITS. LIQUOR A ~ n) x6 Zz < k © fe) =) g | Z O k oO 1g fe) )) o < lJ g = fe) Ng o Zz 6) Z 5 io) a 0 S x fo) 0 | le 2. BATTERY OF PUMPS FOR CIRCULATING BROMINE ABSORPTION Smithsonian Report, 1934.—Stewart Smithsonian Report, 1934.—Stewart PLATE 6 2. ETHYLENE PLANT AND POWER HOUSE. Smithsonian Report, 1934.—Stewart PLATE 7 1. BATTERY OF VALVES FOR CONTROLLING ETHYLENE PRODUCTION. 2. SHIPMENT OF FINISHED ETHYLENE DIBROMIDE. BEFORE PAPYRUS ... BEYOND RAYON’ By Gustavus J. ESsELen, PH. D. President, Gustavus J. Esselen, Inc., Chemical Research and Development, Boston, Mass. We wear it; we live in houses made of it; we record our news and literature upon it; we even take it into our systems with our food. What is it? The answer to this riddle is a material which has been responsible for epoch-making changes in the trend of human affairs throughout the long road up from savagery through barbarism and early civilization to the present time. Everyone is familiar with it, yet few know it. It is not only the most abundant material of the vegetable kingdom, but it is also one of the most important ma- terials on which man has relied throughout the development of civ- ilization. We know it in the forms of cotton and of linen; of wood and of paper. We even know it as artificial silk. Yet ref- erence to cellulose, which is the basic chemical substance common to all these materials, brings in a word which is familiar to few. On the other hand, this term cellulose is one destined to become gradu- ally more and more familar, at least to those who make any pre- tense of following modern trends in the arts and sciences. Cellulose has not only exerted an unusual influence on the progress of mankind in the past, but today it is the basic raw material for great industries. Since it forms the structural framework of all trees and plants, it is available wherever vegetable life occurs. Furthermore, it is one of the few raw materials which is capable of periodic reproduction in enormous quantities, and for this reason, if for no other, seems destined to take an increasingly important part in the industrial development of the world. Since cellulose is so common in nature, it is only natural that it should have played an outstanding role in the history of mankind from the time that early man took the first step out of savagery by accidentally learning how to burn it, until, in the form of a 1 Reprinted by permission from the Journal of the Franklin Institute, vol. 217, no. 3, March 1934. Presented at a meeting of the Franklin Institute held Thursday, Oct. 26, 1933. 169 170 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 “serap of paper” it was responsible for developments leading to the Great War in 1914. Civilization proper is generally considered to have begun with the development of a system of writing, perhaps 10,000 years ago. For this, cellulose can claim no credit, since early writings were on clay and stone long before the advent of papyrus. However, when in more recent years cellulose, as paper, became the silent bearer of the written and later the printed word, it became the messenger of the guiding forces of civilization. It is in this role that cellulose has reached its highest significance, making possible many things which had not been feasible before, through the easy and ready dissemina- tion of information to great masses of people. At about the same time that the manufacture of paper was being introduced into Europe there were also other developments depend- ent upon the use of cellulose which were of such outstanding im- portance as to have changed the whole trend of civilization. It was in the thirteenth century that Roger Bacon? first described black powder, to which he gave the name “philosopher’s egg.” How strikingly time has shown the aptness of this picturesque title and what events of first importance have been hatched from it! When used in guns, as it was in the fourteenth century, it put a new power in the hands of the common people and changed the entire social system. Truly did Bacon write, referring to his anagram in which he gave the secret of gunpowder, “ Whoever will rewrite this will have a key which opens and no man shuts; and when he will shut, no man opens.” And an essential part of this “ key ” was charred cellulose. Again the ready availability of cellulose con- tributed its part to an epoch-making step in the advance of civiliza- tion. Even today charcoal from willow and beech is preferred for the manufacture of black powder. It has been said that this particular period was a great period of leveling; that gunpowder was a great leveling influence downward for the mighty and that the printed page was a great leveling influence upward for the lowly. At any rate paper has now come into universal use throughout the civilized world. It may be only to wrap a bundle or it may be to record a thesis which starts a reformation. It may be to carry a love message or it may be to announce a declaration of independence. It may be merely the kin- dling which lights the fire on the hearth or it may be the scrap of paper which starts a world conflagration. To be sure, paper had been known in China for several hundred years before the Christian era, but its use was not established in Europe until about the twelfth or thirteenth century. The story is 2 Davis, Ind. and Eng. Chem., vol. 20, p. 772, 1928. BEFORE PAPYRUS... BEYOND RAYON—ESSELEN 171 told that the Arabs were attacked by the Chinese in Samarkand about the middle of the eighth century. The Arabs repulsed their enemies and succeeded in capturing some of the Chinese who knew how to make paper and from them learned the secret. The knowledge of papermaking spread rapidly in Arabia as is evidenced by the fact that there are many early Arabian manuscripts on paper still preserved to- day, the earliest being dated A. D. 866. Trade with Asia seems to have been responsible for bringing a knowledge of paper manufacture to Greece at about the end of the eleventh century, and the Moors established it in Spain in the middle of the twelfth. It gradually spread to Italy, Germany, and France, so that by the year 1350 the manufacture and use of paper was well established in Western Europe and vellum was gradually superseded. Today we have many grades and kinds of paper, but all are com- posed mainly of cellulose, of degrees of purity which vary with the particular kind of paper. At first all paper was made from cotton or linen rags, but during the last century wood has become the chief source of supply through the development of chemical methods for separating the cellulose from the other constituents of wood. In 1932 in the United States alone there were consumed about 4,000,000 tons of wood pulp which represents about 9,000,000 tons of wood. Of this, a little more than half was of domestic production and the bal- ance imported. The use of a natural resource at so rapid a rate has naturally raised the question as to the steps which should be taken to prevent exhaustion of the supply. To some, the answer seems to be reforestation, while others prefer to rely on cutting trees only above a certain size. By leaving the smaller trees in this way, it has been demonstrated in several sections in the South that a 20-year crop cycle is perfectly feasible. Many experts believe that if the cellulose resources of the temperate zone should prove inadequate, the Tropics could be relied upon for an adequate supply. Already the rapid- growing bamboo of India is being converted into pulp, and studies are being made of the pulp possibilities of varieties of African trees which yield as much or more cellulose per acre per year. Since cellulose forms the structural skeleton of all vegetable growth, attention is also being focused on annual field crops as possible sources of cellulose. Cornstalks were suggested for paper- making well over 100 years ago, and chemically this has been pos- sible for a long time. However, it is only within the last few years that the economic problems of harvesting, collecting, and storage have received the scientific study which is essential if these problems are to be solved in such a way as to make the use of cornstalks eco- nomically feasible. The sugarcane also has been the object of con- siderable attention and many kinds of paper have been produced 172 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 from it. The application of scientific method in this case has demon- strated in actual farm tests that the per-acre yield of sugarcane can readily be increased fourfold to sixfold, and in special test plots the yield has been raised to 20 or 30 times the usual average. Even with present yields of corn it is estimated that the United States produces annually about 31,000,000 tons of cornstalks. This is dry weight, free from leaves and husks, and should yield, in the form of paper or board, about 9,000,000 tons, or a little more than the total amount of paper and paperboard produced in the United States in 1932. In other words, assuming the solution of economic problems, such as the collection at a central point of sufficient quantities to permit of operation on a proper scale and the storage of enough material to keep such a mill going for the better part of a year, it still would be necessary to find new outlets for cellulose to make the collection of any considerable proportion of the stover from our annual field crops economically desirable at this time. In transportation as in so many other activities, man was long dependent on cellulose. His earliest boats, in the form of hollowed logs, were essentially cellulose, as were the paddles and later the oars that propelled them. The sailing ships on which man relied until so recently, were made of wood and the cloth of the sails was cellulose in a purer form. Even the modern ocean liner requires cellulose in the form of boat covers, collapsible boats, curtains, deck covering, fenders, hatch covers, life preservers, and tarpaulins, not to men- tion what might be termed the household requirements such as sheets, towels, upholstery, draperies, and table damask. For land transportation, also, man long depended on cellulose. His early sledges and carts were of wood, as were also the stage coaches of a later day. The modern limited train, in which cellu- lose now is only of minor importance, is the outgrowth of experi- ments conducted only a hundred years ago in which the fuel was wood, the cars were of wood, and in some instances even the rails were of wood. When we turn to the modern automobile, so essen- tial a part as the tires are quite as much cotton cellulose as they are rubber. While for thousands of years man had turned to cellulose for so many of his needs, it had, until the last 100 years, always been as the naturally occurring cellulose or as the simple derived products, charcoal and paper. With the development of chemistry it was only natural that chemical derivatives of cellulose should begin to make their appearance. The surprising thing to any critical observer might be that the chemistry of cellulose was so slow in developing, since the use of cellulose itself was centuries old. To the BEFORE PAPYRUS... BEYOND RAYON—ESSELEN livia chemist, on the other hand, the reason is quite apparent, for it is only a relatively short time that even the empirical composition of cel- lulose has been known. For some time that was all the information available, since cellulose could not be crystallized nor could its molecular weight be determined. Little by little the chemistry of cellulose has been unfolded and although we do not yet know the whole story, it is nevertheless being recognized that in cellulose, mankind has a chemical raw material available in enormous quanti- ties and a substance the supply of which can be annually replenished when economic conditions become such as to warrant it. At this point it may be of interest to digress a moment to survey briefly the development of industrial organic chemistry. It started with the distillation products from coal as its raw material and separated from this complex mixture various substances of the so-called aromatic series, from which were synthesized at first dyes, and later perfumes and medicinals. In each case, however, the prod- uct was a definite solid or liquid compound with well defined molec- ular properties. About 10 or 12 years ago a second division of applied organic chemistry appeared, which has since grown to what might almost be called a heavy organic chemical industry. It starts with the simplest aliphatic hydrocarbons such as ethylene and builds up from there aliphatic products which find wide use in industry, many of them as solvents. The synthetic processes have even been carried to a point where various polymerized molecules have been produced to give solids with colloidal characteristics such as the vinyl resins and the so-called synthetic rubber. At this point this second division of applied organic chemistry meets the third, which uses cellulose as raw material. Here we have a sub- stance which occurs naturally in the form of a highly polymerized molecule and the uses of it and its derivatives depend in large degree upon the retention of these colloidal properties. In spite of the fact that industries using cellulose are centuries old, it is only for a relatively short time that we have known even that its empirical composition was C,H,,.O;. At first, it was thought that there were four hydroxl groups in the C.H,,O; unit, and I can well remember a lively discussion at one of the meetings of the American Chemical Society not more than 12 years ago as to whether there were four hydroxl groups or only three. It is now generally recognized, that there are only three hydrox] groups in the elementary cellulose unit, but it was not until about 11 years ago that their character was known. This question was answered very prettily by Denham and Wood- house by repeated treatments of cellulose with dimethyl sulphate 174 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 in the presence of alkali. On hydrolyzing the methylated cellulose with weak acid they obtained chiefly 2, 3, 6 trimethyl glucose which may be represented CH,0OH CH,OCH; HC————__ aa soon HCOH HOCH CH,;O0CH b | O 2, 3, 6 trimethyl glucose H : OH | HCOCH; | “i ne HO HO Glucose Since there are two free hydroxyl groups in the trimethyl glucose, it is apparent that these could not have been present in the original cellulose molecule but must have been produced during the hydrol- ysis. The methylated ones are the ones which were originally present in the cellulose and since the constitution of trimethyl glucose is known, it follows that in cellulose there must be three and only three hydroxyl groups, one of which is a primary hydroxyl group and the other two secondary. Since the empirical composition of cellulose is C.H,.O; and that of glucose C.H,.O., it is obvious that cellulose is made up of anhydro-glucose units. This statement, however, would hardly suggest the exceedingly complex character of the cellulose molecule. Although externally cellulose and its derivatives always appear as amorphous or colloidal materials, nevertheless the X-ray has shown them to possess definite crystalline characteristics. The unit cell responsible for the crystal- line properties is believed to consist of four glucose residues. It is now believed that these unit cells are bound together by primary valences into long chains of what might be termed anhydro-glucose residues, and that these primary valence chains are in turn bound together by secondary valence forces to form the micelle. This basic idea has been extended and elaborated to account for the structure of the cellulose fiber, including its high longitudinal strength, the orientation about the long axis of the fiber, and the presence of the outer layer of fibrils in the cellulose fibers from wood. Thanks to recent investigations by Staudinger, by Freudenberg, and by Stamm, we even have some conception of the molecular weight of cellulose. While these figures do not agree, nevertheless, they at least indicate that the molecular weight is very high. Stau- BEFORE PAPYRUS...BEYOND RAYON—ESSELEN 175 dinger, for example, has found that cellulose from purified cotton has a molecular weight of 190,000 and he feels that even this may be on the low side. Freudenberg has calculated the molecular weight to be in the neighborhood of 8,100, although he admits this is prob- ably too low. Stamm, using the ultracentrifuge, has obtained a molecular weight in the neighborhood of 40,000. In this connection it is of interest to note that Staudinger and Schweitzer found that rayon made by the cuprammonium process has a molecular weight only about one-sixth that of purified cotton, and Stamm found that the cellulose in wood pulp consisted largely of material having a molecular weight about half that of cellulose from carefully purified cotton. Although the use of cellulose as a technical raw material did not wait for our present-day knowledge of the structure of the cellulose molecule, nevertheless, the more we know about the inner chemistry of cellulose, the more rapidly do its uses expand. The first chemical derivative of cellulose to assume importance in our present-day civilization was the nitrate. When a properly purified cellulose is treated with a mixture of nitric and sulfuric acids. a series of nitric acid esters of cellulose is formed. Those which contain about 11 percent of nitrogen are the basis of the pyroxylin plastics such as celluloid; those with about 12 percent of nitrogen are used for artificial leather and lacquer finishes; while those with a higher percentage of nitrogen constitute our smokeless powders. The significance of the last for present-day civilization needs no comment. The modern pyroxylin finishes, as represented by quick- drying lacquers, have been as effective in their way in increasing man-hour output as has power machinery in other ways. Nitrocel- lulose and cellulose acetate, as the basis of the moving-picture film, have given us a means of recording events in action and in sound as they previously had been recorded in story on.cellulose in the form of paper. One of the uses of transparent sheets of cellulose ester plastic which is now receiving considerable attention in the public eye is in the manufacture of laminated glass such as is finding increasing use in the modern automobile. This glass is made by cementing a specially prepared sheet of cellulose plastic material between two pieces of glass. The product as used in windshields is of about the same thickness as ordinary plate glass but it does not shatter nor do the pieces fly when the glass is broken. A further application of the same principle is in the manufacture of bullet-proof glass. This is 3 Since writing the above, the author has been advised privately that recent and more accurate determinations have placed the molecular weight of carefully purified cotton Cellulose at 300,000. 176 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 composed of five laminations. The center one is usually a piece of plate glass about three-quarters of an inch in thickness. To each side of this is cemented a sheet of cellulose plastic and on the outside of each of these layers of plastic there is cemented a piece of thinner plate glass, making a composite piece a little over an inch thick. Such material resists bullets even at close range and is finding use in the windows of armored cars and cashiers’ cages in banks. Up until very recently the plastic used for this purpose was made from cellulose nitrate. This was not ideal for the purpose because it gradually discolored in the light. However, considerations of cost compelled its use. Within the last year or so, however, a revolu- tionary change in the method of manufacture of these plastics has so lowered the cost of the finished sheets of cellulose acetate plastic that at the present time it is estimated that over 70 percent of all the laminated glass manufactured in this country is made with cellulose acetate plastic. The manufacturing improvement responsible for this surprising change consists in replacing a long series of batch operations by a single continuous process which cuts the time of production from 10 or 12 days to the corresponding number of hours; and since the material is totally enclosed during its manufac- ture, practically the total production is of first quality. When attention is turned to the manifold applications of cellulose and its derivatives in modern civilization, it becomes quite apparent that cellulose is not only nature’s riddle but also nature’s paradox. Cellulose in the form of wood has long been used as a material of construction because of its resistance to atmospheric conditions, yet at temperatures slightly under that of boiling water, cellulose slowly combines with oxygen and decomposes. Again cellulose in the form of cotton is widely used for clothing because of its resistance to washing and to the chemicals usually used in that operation, yet two samples of cellulose, identical except that one has been boiled in distilled water for 2 hours and then dried, exhibit markedly different chemical characteristics, We therefore find that to supplement the age-long uses of cellulose which have been dependent on its resistance to chemical change, there is now springing up a long list of uses which depend upon its chemical reactivity. If cellulose in the form of cotton thread or fabric is treated with an 18 percent solution of caustic soda in the cold and dried under tension, there is obtained the well-known effect of mercerization which produces a silky finish on cotton fabrics. On the other hand, if sulfuric acid of about 70 percent strength is used instead of the caustic soda and the acid thoroughly washed out, there is obtained the material known as vegetable parchment, which is sufficiently water resistant so that it has been sold to replace cloths BEFORE PAPYRUS...BEYOND RAYON—ESSELEN rf 7/ in dish-washing. Paper is the form of cellulose used for this treat- ment. When special forms of paper are employed, the product makes an excellent electric insulation. Treatment with concen- trated solutions of zinc chloride produces a somewhat analogous effect, the product being known as vulcanized fiber which finds many uses in industry as for example in roving “cans” so-called, and trucks for textile mills. For centuries cellulose in the form of linen and cotton, has pro- vided wearing apparel. Almost our earliest literature speaks of purple and fine linen. Yet silk was always the fabric of the no- bility and had a beauty and a feel which the cellulose fibers could not match. Since the sheep converted the cellulose of hay and grass into wool and the silk worm changed the cellulose of the mul- berry leaf into silk, man has long been trying to find the secrets, par- ticularly that of the silk worm. The natural raw material with which to experiment was cellulose, at first that of the mulberry leaf and later a purified cellulose. While the silk worm’s secret has not yet been found, ways have been developed, after years of research, for producing from cellulose fibers which are as attractive as silk to both eye and skin. In the four forms of rayon we have the first man-made fibers and fibers which, therefore, are not subject to the whims of nature for their production. The goal for which the early investigators in this field were striv- ing, was the production of natural silk by artificial means. In fact it has been said that its earliest designation, artificial silk, was given to the new product in order to distinguish the silk made by artificial means from that made by nature. It is well known now, however, that none of the four varieties of rayon are in any way related chemically to silk. The first three to be developed are all regen- erated cellulose and quite similar in their properties, although the series of changes through which they have passed from cellulose to finished product are in each case quite different. ‘The latest member of the group is cellulose acetate, a chemical compound of cellulose and acetic acid and quite different in its properties from either cellu- lose or the other forms of rayon. In general the processes for the manufacture of synthetic fibers may be divided into two classes, depending upon whether the finished fiber is essentially cellulose, regenerated in a somewhat modified form, or whether it is a compound of cellulose such as cellulose ace- tate. All of the processes have certain underlying principles in com- mon, involving first the conversion of the cellulose into a soluble derivative, the solution of which is then forced through very fine ori- fices into a hardening medium which may be either a liquid or a gas, depending upon the character of the solvent. In the earliest process, 178 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 the cellulose was converted to cellulose nitrate which was dissolved in a mixture of alcohol and ether, and this solution, after careful filtration, was squirted through fine orifices into a stream of warm air which caused the solvent to evaporate, leaving fine filaments of cellulose nitrate. The solvents were recovered and the fibers sub- jected to an alkaline saponification treatment for the purpose of reducing their inflammability. This left them finally in the form of regenerated cellulose. This process is now being used by only a single company in the United States. Another process takes advantage of the solubility of cellulose in cuprammonium solutions. In this case the deep blue, viscous cellu- losic solution passes from the fine orifices directly into a liquid regen- erating bath which may be either a dilute acid or a dilute alkali. After being freed from copper, these fibers also are composed of regenerated cellulose. The process by which at least 80 percent of the artificial silk is produced today, is the viscose process. In its barest outline it con- sists in treating purified cellulose with caustic soda solution, followed, after a suitable aging period, by treatment with carbon bisulfide which produces a cellulosic compound soluble in dilute alkali. This also is ripened and then squirted into dilute sulfuric acid which breaks down the soluble compound and regenerates the cellulose. In all of these three processes it will be noted that the finished fibers are composed of a modified cellulose. In the fourth commer- cial process and the one which just now is expanding at the most rapid rate, the cellulose is converted into cellulose acetate and the finished fibers are composed of the same material. The solvent is usually acetone and the solution is ejected from the orifices into a stream of air in which the acetone evaporates and from which it is recovered. One of the advantages of this process is that the fibers require no further chemical purification treatment before they are ready for what might be called the textile operation of twisting. When artificial silk first appeared on the market it was rather coarse and somewhat harsh in its feel. Since then, however, there have been marked improvements in the strength of the fibers and, also, there has been a general tendency toward reducing the size of the individual filaments as well as the size of the threads. Per- haps one of the most remarkable developments in the rayon industry in recent years has been the marked increase in the demand for fibers in which the normally high luster has been reduced. Originally artificial silk achieved popularity because of its high luster, yet today considerably more than half of all the rayon produced has the luster more or less reduced. BEFORE PAPYRUS... BEYOND RAYON—ESSELEN 179 Still another trend which is worth noting, is the increasing popu- larity of synthetic fibers made from cellulose acetate. This was the last of the four varieties to achieve commercial importance, and at first its high cost deterred is wide use. Recently, however, there have been reductions in the price and with these have come wider markets. When rayon, or artificial silk as it was then known, first began to attract attention in this country, a committee of silk manufac- turers was appointed to study this new competitor and report on its possibilities. After careful deliberation the committee finally con- cluded that the possibilities of the new fibers were distinctly limited and that they would probably be short-lived. Yet in 1931 60 percent more rayon was used in the United States than natural silk and this year the proportion in favor of rayon is probably even higher. Rayon, however, should not be looked upon as a substitute for silk, but rather as unique fibers with distinct and valuable properties of their own. These fibers may be used alone in fabrics; in conjunction with cotton to furnish an attractive decorative effect; or with wool to produce pleasing new fabrics of lowered cost. New applications are constantly being found. In 1910 the production of rayon in the whole world was only about 10,000,000 pounds, and none was being made in the United States. In 1928, on the other hand, 100,000,000 pounds were turned out in the United States alone, and in 1931 the production here amounted to about 144,000,000 pounds, the figure for 1932 being 10 percent less than for 1931.* In spite of the rapid developments of the last few years, it is doubtful whether the real significance of these new fibers has yet been visualized by anyone. When first produced in this country 20 years ago they lacked strength and resistance to water but improve- ment in these and other directions has been constant. A special type of rayon fiber has been developed which rivals silk in appear- ance and strength even when wet, though certain other characteristics have thus far prevented its wide introduction into the textile industry. Even beyond rayon, cellulose is continuing to be a powerful aid in making possible new developments which are changing the whole trend of civilization. For the airplane, as in earlier forms of trans- portation, cellulose was the first material to which man turned. The framework and propeller were made of wood, the wings were cov- ered with cellulose in the form of linen or cotton fabrics, and these in turn coated with cellulose nitrate or cellulose acetate varnishes to *It is of interest to note that rayon production in 1933 amounted to 208,530,000 pounds, an increase of 60 percent over the preceding year. 111666—35 13 180 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 render them taut. Whatever the future of the metal airplane, the availability of cellulose and its remarkable adaptability have helped markedly in the progress of aviation. The merchandising of packaged articles is today dependent to a very large extent upon cellulose. The large container or carton is made from paper board as are the smaller boxes which hold the in- dividual units of merchandise. To increase the appeal to the eye, the chemist in recent years has furnished transparent sheets of Cello- phane and Sylphwrap. The chemistry involved in the manufacture of this material is the same as that of the viscose process for manu- facturing artificial silk, but instead of extruding the cellulosic solu- tion through minute orifices it is forced through a long narrow slot into a hardening bath. Another new use for a cellulose derivative is in the manufacture of shoes. In this novel process all sewing or nailing of the shoe is eliminated and the shoes are literally stuck together. The cement used is a specially compounded cellulose nitrate cement with unusu- ally rapid sticking qualities. When the process was first used in the United States in 1928 the soles had to be held in contact with the uppers for 30 minutes. At the present time the process has been so perfected that it is now only necessary to hold the two parts together for 50 seconds. The process is so rapid that a single operator in 8 hours and 15 minutes applied soles to 1,580 pairs of shoes. The indi- cations are that over 50,000 pairs of shoes will be made by this method in the United States in 1933. In this new age cellulose has taken its place as a great chemical raw material, and with increasing knowledge its importance is bound to be enhanced. Technical literature and patent indices are record- ing at an increasing rate new chemical derivatives of cellulose, many of which may reasonably be expected to appear in industry within the next 5 or 6 years. Already cellulose ethers are available, some of which have a very unusual resistance to both acid and alkaline solutions. Reports are also being heard with increasing frequency of new mixed esters with greatly improved properties. It is only the complex chemical character of cellulose that has so long delayed its utilization as a raw material for chemical transformation, but as the nature of the cellulose molecule continues to be elucidated a material of which so large a supply is potentially available will surely find useful application in increasing quantities. THE VARIETY IN TIDES* By H. A. MARMER United States Coast and Geodetic Survey The usual explanation of the tide in textbooks of physical geog- raphy or astronomy makes of it a simple phenomenon. It is shown that the gravitational attraction of sun and moon on the earth gives rise to forces which move the waters of the sea relative to the solid earth. It is further shown that these forces have different periods, but that the predominant ones have a period of about half a day; therefore there are two high waters and two low waters in a day. And finally it is shown that the moon plays the leading role in bringing about the tide, for the tide-producing power of a heavenly body varies directly as its mass and inversely as the cube of its distance from the earth. On the bases of these general considerations, numerous features of the tide can be explained. Thus, at the times of new and full moon, when the tide-producing forces of sun and moon are in the same phase, the tides are greater than usual, while at the times of the moon’s quadratures the tides are less than usual. In the same way, when the moon is in perigee, or nearest the earth, greater tides result than when the moon is in apogee or farthest from the earth. To be sure, it is known that the tides at different places vary in time, in range, and in other features. But these differences are ascribed to modifications brought about by local hydrographic fea- tures. And thus the whole phenomenon is seemingly reduced to simple terms. To the navigator who is familiar with the Seven Seas, however, this very much oversimplifies the subject. For he finds that the tides at different places vary not only in time and in range, but also in character of rise and fall. Quite apart from differences in time and in range, which may be regarded as merely differences in degree, it is found that tides present striking differences in kind. There is, in fact, an almost bewildering variety in tides. Take for example the actual records of the rise and fall of the tide at three such well-known places as Norfolk, Va., Pensacola, 1 Reprinted by permission from the United States Naval Institute Proceedings, vol. 60, no. 3, whole no. 373, March 1934. Copyrighted: United States Naval Institute, Annapolis, Md. 181 182 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 Fla., and San Francisco, Calif., for the last 4 days of May 1931. These are shown in figure 1, the horizontal line associated with each tide curve representing the undisturbed or mean level of the sea. At Norfolk, it is seen, there are two high and two low waters in a day, morning and afternoon tides differing but little, and the high Figur® 1.—Tide curves, Norfolk, Pensacola, and San Francisco, May 28-31, 1931. waters rising approximately the same distance above sea level as the low waters fall below it. At Pensacola, on the same days, there were but one high and one low water each day. And at San Francisco, while there were two high and two low waters each day, the morn- ing tides differed very considerably from the afternoon tides. It must be emphasized that the differences in the tides at the three places shown in figure 1 are in no way due to the disturbing VARIETY IN TIDES—MARMER 183 effects of wind or weather. Heavy winds and rapid variations in barometric pressure do bring about very marked changes in the rise and fall of the tide. But the last 4 days of May 1931 were pur- posely chosen because weather conditions then were relatively uni- form. The features exhibited by the tides shown in figure 1 are characteristic features of the tide at the three places. Ficurp 2.—Tide curves, Seattle, Honolulu, and San Diego, May 28-31, 19381. If we go to other places we find yet other varieties of tides. In figure 2 are shown the actual records of the tide for the same 4 days of May 1931 at Seattle, Wash., Honolulu, Hawaii, and San Diego, Calif. At each of these places it is seen that there are 2 high and 2 low waters in a day. At Seattle, however, morning and afternoon high waters do not differ much, while the morning and afternoon low waters differ strikingly. On the last day shown in figure 2 the afternoon low water was 10.5 feet higher than the 184 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 morning low water. At Honolulu, conditions are the exact reverse of those at Seattle, for at the former place the differences between morning and afternoon tides are exhibited principally by the high waters. It is of interest to note, too, that, during the last 2 days, the afternoon low waters at Seattle did not fall as low as sea level, while at Honolulu the morning high waters did not rise as high as sea level. In contrast with conditions at Seattle and Honolulu, the tide curve for San Diego shows the differences between morning and afternoon tides to be exhibited in approximately equal degree by Figure 3.—'Tide curves, Galveston and Manila, May 28-31. both high and low waters. The tide curve for San Diego looks much like that at San Francisco shown in the bottom diagram of figure 1. At the latter place, however, it is seen that there is a greater dif- ference between the two low waters of a day than between the high waters. Now it is a well-known fact that at any place the tide has local features with regard to times of high and low water, range of tide, or characteristics of rise and fall which distinguish it from the tide at other places. But in the tides represented in figures 1 and 2, time and range were disregarded, and the features considered were not minor differences but characteristics of a fundamental nature. In other words the tides at these places constitute distinct varieties. VARIETY IN TIDES—MARMER 185 The varieties of tides considered above do not, however, exhaust the variety in tides. In figure 3 are shown the records of the tides at Galveston, Tex., and at Manila, P. I., for the same 4 days of May 1931. At Galveston, for the first 2 days, there are 2 high and 2 low waters each day; but for the last 2 days, there are but 1 high and 1 low water a day. A characteristic feature of the tide during these last 2 days is the long stand of the tide which begins about 4 hours after high water, when for a period of about 3 or 4 hours the tide changes but little in height. At Manila, there is a somewhat similar state of affairs; but whereas the stand of the tide here takes place on the rising tide, at Galveston it takes place on the falling tide. Furthermore, the stand of the tide at Galveston occurs above sea level, while at Manila it takes place below sea level. On investigation it will be found that most tides can be referred to one or another of the varieties discussed above. Furthermore, it can be shown that these different varieties arise from different combina- tions of two primary constituent tides. In developing the tide- producing forces arising from the attraction of sun and moon, it is found that these forces have different periods, the principal ones being those having a period of a day and of half a day, respectively. The daily tide-producing forces give rise to a tidal constituent hav- ing a period of a day, and the semidaily forces give rise to a tidal constituent having a period of half a day. And it is the varying combinations of these two constituent tides that give rise to the dif- ferent varieties discussed. An example will make this clear. Suppose that in a certain sea the tide-producing forces give rise to daily and semidaily tides with different ranges. If the semidaily constituent has much the greater range, it is clear that within that sea the tide will be much like that at Norfolk, morning and afternoon tides differing but little, and the tide will be of the semidaily type. If the range of the daily constituent is much the larger the tide will be like that at Pensacola with but one high and one low water in a day, or of the daily type. But suppose that the two constituent tides have the same range, what is the character of the resultant tide? The rise and fall of each of these constituent tides may be represented as in figure 4, the semi- daily constituent by the dotted curve and the daily constituent by the dashed curve. The height of the resultant tide at any moment is then clearly the sum of the heights of the constituent tides at that moment. In figure 4 the resultant tide is indicated by the heavy full-line curve. Now the two constituent tides may combine in various ways in regard to time. In figure 4 three cases are considered. In the upper 186 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 diagram the two constituent tides have such time relations that their low waters occur at the same time. The resultant tide in this case resembles the tide at Seattle, the differences between morning and afternoon tides being wholly in the low waters. The middle diagram represents the case in which the high waters of the two constituent tides occur at the same time, and now the resultant tide resembles that at Honolulu, the differences between morning and afternoon tides being exhibited wholly in the high waters. Finally, the lower diagram represents the conditions resulting when the two constituent tides are at sea level at the same time. Now the resultant tide resembles that at San Diego, the differences in the morning and _ after- noon tides being exhibited in equal degree by both high and low waters. It appears, therefore, that the varieties of tides represented by such tides as at Seattle, Honolulu, and San Diego arise from a mixture of daily and semidaily tides of ap- proximately equal range. Such tides are known as the mixed type. Tides in which a stand occurs, as at Galveston and Manila, can be shown to arise from a combina- tion of a daily and a semi- daily constituent in which the former has twice the range of the latter. If in the case repre- sented by the lower diagram of figure 4, we take the range of the daily constituent twice that of the semidaily, it is found that the resultant tide will have but one high and one low water with a stand on the rising tide. If we take the two constituents such that are at sea level at the same instant, but both rising instead of falling, as in figure 4, the stand will occur on the falling tide. And it is to be noted that both the daily and semidaily tide-producing forces vary in intensity from day to day, the former being greatest when the Ficgurn 4.—Combination of daily and semidaily constituent tides VARIETY IN TIDES—-MARMER 187 moon is at its semimonthly maximum north or south declination, and the latter being greatest when the moon is over the Equator. It is in this varying relation of the magnitudes of the daily and semidaily tide-producing forces through a fortnight that we find explanation of tides which part of the time are of the mixed type and part of the time of the daily type. The strikingly different characteristics of the varieties of tides discussed above have been traced back to the combination of daily and semidaily constituent tides of different times and ranges. The question that immediately arises is, why do the waters of the sea in different places respond differently to the tide-producing forces of sun and moon? For these tide-producing forces are distributed in a regular manner over the entire earth. To answer this question it is necessary to consider the physics of the movement of bodies of water under the impulse of periodic forces. Briefly, it may be stated that a body of water has a natural period of oscillation which depends on the length and depth of the body of water. Furthermore, when disturbed by periodic forces that tend to upset its equilibrium, a body of water will respond best to that force the period of which most closely approximates to its natural period of oscillation. The principal tide-producing forces of sun and moon, as has been noted before, are those having periods of half a day and a day, respectively. As these tide-producing forces sweep over the earth they put into oscillation the waters of the various oceanic basins. But the response of any given oceanic basin to these forces depends on the natural period of oscillation, which period is determined by the length and depth of the basin. Those basins whose natural periods of oscillation approximate to half a day respond best to the semidaily tide-producing forces; hence the semidaily constituent of the tide will predominate and the tide in these basins will be of the semidaily type. Those bodies of water whose natural periods of oscillation approximate to a day will re- spond best to the daily tide-producing forces and thus give rise to daily tides. At the same time, those bodies of water, the natural periods of oscillation of which approximate to the daily forces as closely as to the semidaily forces, will respond in approximately equal degree to both kinds of tide-producing forces and hence give rise to mixed tides. The varieties of tides described above are those most frequently met with in the large world ports. There are places, however, where local hydrographic features give rise to peculiarities not found at other places. Along the open sea and in coastal bodies of water, the durations of rise and fall of tide are approximately equal. This gives the rising and falling portions of the tide curve a symmetrical 188 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 appearance with regard to high or low water. Im the upper reaches of tidal rivers, however, especially where there is considerable fresh- water discharge, this is not the case. Thus at Albany, near the head of tide water on the Hudson River, at times of freshets the tide may rise for 3 or 4 hours and fall for 8 or 9 hours. This gives the tide curve in such rivers a characteristic appearance, the rise being repre- sented by a short steep line, while the fall is represented by a longer gently-sloping line. This feature in river tides is obviously due to the resistance of the river bottom and banks to the upstream progress of the tide. Furthermore, the drainage waters which find their way into a river give rise to a current that tends to flow downstream constantly. This acts as an added element of resistance to the progress of the tide upstream. And thus the duration of rise of tide is shortened, while the duration of fall is correspondingly lengthened. In certain rivers the tide during a portion of its rise comes as a wall of water several feet in height. This phenomenon is known as a bore and is found to occur in the upper regions of tidal rivers having large ranges of tide, the channels of which are obstructed by bars and mud flats. This may be considered as the limiting case of river tides, in which the steepness of the rising tide becomes so great as to become vertical during a part of the rise. In North America the best known bore is that occurring in the Petitcodiac River in Canada. The largest bore is probably that found in the Tsientang, a Chinese river which empties into the China Sea. In this river the bore comes as a wall of water 10 feet or more in height, its front a sloping cascade of bubbling foam. Throughout the world, with but rare exception, the sovereignty of the moon over the tide is clearly exhibited by the retardation in the times of high and low water by about 50 minutes each day. Thus in figure 1 it is seen that the first high water of May 28 at Norfolk occurred at 6 o’clock and that each day thereafter it came about an hour later. The other high water and also the low waters are seen to have occurred approximately an hour later each day. And at Seattle, with a totally different kind of tide, a similar re- tardation in the times of high and low water is seen to have occurred. This merely confirms the old adage that “ the tide follows the moon.” For the transit of the moon over any place occurs each day later by 50 minutes, on the average. There are some places, however, where the tide appears to follow the sun rather than the moon. That is, instead of coming later each day by about 50 minutes, the tide comes to high and low water at about the same time day after day. Thus at Tahiti in the Society Islands, it has been known for many years that high water generally comes about noon and midnight and low water about 6 a. m. and VARIETY IN TIDES—MARMER 189 6 p.m. In fact, it appears that the natives use the same word for midnight as for high water. At Tahiti, therefore, the tide is solar rather than lunar. The range of the tide at Tahiti is small, less than a foot on the average. A better example of the solar type of tide has recently come to light at Tuesday Island, a small island in Torres Strait, lying about 15 miles northwesterly from the northern point of the o* Ge 12 is” 24h FIGURE 5.—Tide curves, Tuesday Island, Sept. 10-16, 1925, Australian mainland. Here the range of the tide averages nearly 5 feet. The peculiar behavior of the tide here with regard to time is clearly brought out if the tide curves for a number of days are arranged in column, as in figure 5, which represents the tide curves for each day of the week beginning September 10, 1925. It will be noted that the high and low waters in this figure fall practically in a vertical line; which means that instead of comimg later each day by about 50 minutes, which is the state of affairs at 190 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 most places in the world, the tide here comes about the same time day after day. That this is not a general feature of the tides in the South Pacific Ocean is evident from a comparison with the tide curves for Apia, Samoa, for the same week, which are shown in figure 6. It will be noted that here there is a distinct shift to the right in regard to the times of high and low water in following down the curves. Figure 6.—Tide curves, Apia, Sept. 10-16, 1925. The mathematical process of harmonic analysis permits the tide at any place to be resolved into its simple constituent tides. At Apia the principal lunar constituent has a range of 2.5 feet, while the principal solar constituent has a range of 0.6 foot. Hence the tide here follows the moon. At Tuesday Island, the principal lunar and solar constituents both have the same range of 3.1 feet. Hence here the tide is no longer predominantly lunar but as much solar as lunar. The answer to the question as to why the tide at some places is governed by the sun rather than the moon is again found in the physi- cal characteristics of the various oceanic basins and seas. Where the VARIETY IN TIDES—MARMER 191 conditions are such as to restrict the response to the lunar tide-pro- ducing forces but not the response to the solar tide-producing forces, the latter become the more prominent and give rise to solar tides. An interesting form of tide is found at Jolo, in the Sulu Archi- pelago, P. I. Here the high waters follow the moon but the low waters appear to follow the sun. The tide curves for the week be- ginning September 10, 1925, at Jolo are shown in figure 7. The tide 6" TOR 180 24" Feet FiGuRE 7.—Tide curves, Jolo, Sept. 10-16, 1925. here is complicated by the fact that for part of the month there are two high and two low waters in a day, while at other times there is but one high and one low water. It is seen, however, that the high waters exhibit the distinct shift to the right characteristic of lunar tides, while the low waters lie almost perpendicularly under each other. Because of the profound influence of the hydrographic features of a body of water on the movement of the waters in response to the tide-producing forces, various other peculiarities of the tide are found at different places. But the varieties discussed above consti- tute the more important and most generally found varieties of the tide. Teng ORE, diet ot ates watt mango? 7 Japan sooh puma ll wun aspilt incor ai bo. Soney 10 jarsh joa lig oa ai eat saikie dx alyilve cats te ol aew wol oud bas lass digit ory ale Meaeiwod’ Lays af Ot, ai : ana veneer ot, ot LYige oe ie | aaa stode sticas: ails nil 4 » benrparel dig Dee a ial Vane . ‘lye tidied) Ay ie ave imcmmnge MODERN SEISMOLOGY’ By F. J. Scrase Kew Observatory INTRODUCTION As the main branches of science expand and overlap each other, new subdivisions become recognized. Geophysics is a conspicuous instance of such subdivision, and it is one in which there has been a considerable development of interest in recent years. In view of this development the National Research Council at Washington has thought it desirable to prepare a series of bulletins on the physics of the earth with the object of giving scientists who have no special knowledge of the subject some idea of the present position of geophysics and its main problems. Several bulletins of this series have already appeared, the most recent being one on seis- mology.? The authors of this volume, viz, J. B. Macelwane, H. O. Wood, H. F. Reid, J. A. Anderson, and P. Byerly, are all well-known seismologists, and their symposium forms a clear and compre- hensive survey, mainly from the physical standpoint, of modern ideas on the subject. In the present article it is not intended to give more than a brief outline of these ideas; those readers who feel encouraged to enter more deeply into the subject will find the National Research Council’s bulletin a useful guide to further study of the physics of earthquakes. THE GROWTH OF MODERN SEISMOLOGY Before the latter part of the last century seismology did not offer a very attractive field to scientific men, mainly because the data then available were crude and unreliable. That the subject has now taken its place as a quantitative physical science is due, in no small measure, to the pioneer work of John Milne, whose 1 Reprinted by permission, with slight alterations, from Science Progress, no. 113, July 1934, published by Edward Arnold & Co., London. 2 Bulletin of the National Research Council, no. 90. ‘Physics of the Earth, vol. 6; Seismology. Pp. viii-+233 (Washington, D. C.: Nationa] Academy of Sciences, 1933) Paper, $2; cloth, $2.50. 193 194. ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 interest in the subject was roused by his experience of earthquakes during the period 1876 to 1895 when he was professor of mining and mineralogy in Japan. The subject was also taken up by workers in Germany and Italy about the same time, and very soon various types of apparatus were devised to record earthquakes at great distances. On his return to England in 1895 Milne set up his own earthquake observatory at Shide in the Isle of Wight, and in 1897 he inaugurated a scheme whereby recording instruments were installed at a number of stations in various parts of the globe. The observatory at Shide became the central office of a world-wide seismic survey, and the comparative data thus obtained soon laid bare the main facts regarding the propagation of earth tremors through and round the world. A great advance was made at the beginning of the present century, when Wiechert and his pupils at Gottingen took up the question of the interpretation of seis- mograms both from the observational and the theoretical side, and showed how the results lead to a knowledge of the physical properties of the earth. When Milne died in 1913, the organization which he had built up passed into the hands of the late Prof. H. H. Turner, who had shared Milne’s enthusiasm in the work for many years. In addition to his other duties Turner found time for much research in seismology, notably on earthquake periodicities and ieep earthquakes, and his interest in the subject lasted right up to the last conscious minutes of his life, for the collapse which led to his death occurred while he was in the presidential chair of the International Seismological Association at the Stockholm Con- gress in August 1930. Progress in seismology is dependent to a very large extent on international cooperation, and for this reason alone the subject is deserving of all the support we can give it. Since the war the number of observing stations in the world-wide network has in- creased nearly threefold; at the present time there are nearly 400. Practically every country in the world takes a share in the obser- vations. The work, started by Milne and continued by Turner, of collecting data and issuing a summary of the results is still under- taken in England, at the University Observatory, Oxford, under the auspices of the British Association. In addition to the routine work of recording and measuring earthquakes a large amount of seismological research is now being done in many countries, and this is leading to an increased knowledge of the properties of the earth. HOW EARTHQUAKES OCCUR The earth’s crust has by no means reached a stable state; it is con- tinually undergoing deformation under the influence of stresses MODERN SEISMOLOGY—SCRASE 195 which develop within it. The deformation frequently takes the form of a sudden fracture in which the energy stored up by the strain is converted into the energy of internal motion. At the surface of fracture a displacement occurs which sets up vibrations that spread throughout the earth. The majority of severe earth- quakes are produced in this way; such earthquakes are said to be tectonic in origin to distinguish them from shocks caused by stresses arising from volcanic activity. The class of tectonic earth- quakes is by far the larger and more important one; most of the shocks that occur in volcanic regions are small in total energy. Sometimes, however, shocks of greater violence appear to be associ- ated with volcanic eruptions, but it is doubtful whether these earth- quakes are truly volcanic in origin. Whatever its origin, an earthquake sets up a disturbance of the ground which is communicated to other parts of the earth in the form of waves. Since the waves spread out in all directions, the motion of the ground at places distant from the origin of the shock is in general very small. With suitable recording apparatus, how- ever, it can be detected even at the opposite end of the earth. In general, any earth movement may be considered as made up of three linear displacements along directions at right angles to each other. A fully equipped observing station therefore requires three seis- mographs, and the components of the displacement which these are set to record are usually the north-south, the east-west, and the vertical. Many stations, however, only record the horizontal com- ponents, since vertical seismographs are generally more trouble- some to operate. THE SEISMOGRAPH The main principle of the seismograph may be explained briefly as follows: A body attached rigidly to the ground will undergo the same displacement as the ground itself. If, however, the attach- ment is not rigid there will be some relative motion between the body and the ground, and it is this relative motion which enables us to determine how the ground itself is moving. Thus the essential part of a seismograph is like a pendulum, the bob of which tends to remain stationary in space while everything to which it is attached is moving. Actually the bob does not remain stationary, because it is impossible to eliminate entirely the effect of the attachment, but in certain circumstances it is possible to make allowance for this and so obtain the true motion of the ground. The modern devel- opment of seismographs has been in the direction of providing increased magnification of the relative motion and of insuring ade- quate damping of the moving system. The latter is necessary, since 111666—35——14 196 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 any undamped oscillatory system has a period of its own irrespective of the period of the vibrations which are forced upon it, and in such a case the motion recorded bears no definite relation to the true earth motion. For magnifying the movement of the pendu- lum mechanical lever arrangements are tending to be displaced by optical or electromagnetic methods of recording which have the advantage of eliminating friction. In some of the older types of seismographs the weight of the main mass of the pendulum often ran into hundredweights or even tons; it is now realized that such heavy systems are not necessary, and the tendency now is to go to the other extreme. The moving mass of the Wood-Anderson seis- mograph, for instance, weighs no more than a few grams, and whereas most other horizontal instruments use gravity as the restoring force this instrument empleys the torsion of a stretched fiber. In vertical seismographs a coiled spring is generally used to control the motion of the pendulum, and the chief difficulty associated with these instru- ments is the effect of temperature on the elastic constants of the spring. This has been overcome to some extent by the use of elinvar alloy, but there is still plenty of room for improvement in the design of vertical seismographs. : Sb. Ord. Pteraspida.::::> Sb. Ord. Psammostei da: 2Un. Kl. Cyclostomi. Ord. Myxinoidei.- 1Avd. Placodermi | Un.Kl. Arthrodira. Ord. Acanthaspida.------~ = Ord, Coccosteida... 20rd. Petalichthyda.---> 0rd. Rhenanida. 38800 DOG DINE pz Un. Kl. Anthiarchte:s 2Avd. Elasmobranchi. Un Kl, Acanthodi.-: Un. Kl. Holocephalli.- Un. Kl Selachit.: io 3Avd, Teleostomi. CO] Unk. Crossopterygiie Un.Kl. Di pnot.- seippuby. Un. KI. Actinopterygii. Grp. Chondrostei: hts Grp Holostei..-. pert: =\Klasse Amphibia. (ip Se 8 ee Sa - SoS Paes at FiGuRE 1.—-Systematic subdivisions of fishlike forms and fishes based upon the recent investigations. Agnaths, the forms without jaws, comprising only one class—the Ostra- coderms. Gnathostoms, or forms with true jaws, comprising in addition to the fishes all other vertebrates (amphibians, reptiles, birds, and mammals). According to Stensi6’s investigations the Placoderms must be regarded as belonging to the Elasmo- branchs. (Modified after Gross.) HOW THE FISHES LEARNED TO SWIM—HEINTZ 225 the fossil remains, but have also endeavored to analyze them and reconstruct them not only in regard to their skeleton but also in regard to their apparent adaptations and manner of life, in a word, their biology. The efforts have then been particularly directed to- ward the elucidation of the relationship between form and function in the various fossil animals, and to solve this problem wide use has been made of comparisons between fossil and recent forms. During later years Osborn in America and Abel in Germany, among others, have worked very intensively in this direction. Abel has even intro- duced a new name for this branch of paleontology which he has designated as paleobiology, i. e., the investigation of the manner of life of the extinct animals. In this article I will attempt to deal with some aspects of the bi- ology of the oldest known vertebrates, the fishes and fishlike forms. Through analysis of their structures it is possible to show the grad- ual change in their adaptations and to draw various general con- clusions from this. Investigations of the biology of different groups of Paleozoic fishes have been undertaken by many others (e. g., Kiaer, Jaekel, Abel), but so far as I know there has been no previous attempt to give a comprehensive picture of the gradual development of the different adaptations of these peculiar forms. I shall therefore attempt to say a few words about the biology of the oldest known fishes and fishlike forms, that is, the biology of the Placoderms and Ostracoderms. They have all lived in the water, and it is therefore of great interest to attempt to elucidate their adaptations to life and to movement in the water, that is to swimming. But before we proceed to a discussion of these forms in greater detail, it will be better to review briefly the adaptations to swimming which we find among other vertebrates.* It is possible to distinguish three separate groups of organs in all swimming animals: (1) the organs which cause the forward motion itself, that is the organs of locomotion proper, or propulsion, (2) the organs of balance serving to maintain the equilibrium of the ani- mal, and finally, (3) the steering organ by which the direction of the motion is determined, up or down, right or left. These different groups of organs may be very differently developed in different kinds of animals, but all the various modifications, in which adapta- tions to movement through water are found, may nevertheless be classified into four main groups or types. The first type, which also represents the most perfect one, is best shown by the free-swimming fishes (fig. 2, A, B,C). We might for 2More detailed descriptions of the different forms of adaptation among swimming vertebrates can be found in Abel’s ‘“‘ Palaeobiologie ”, 1912. 226 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 instance consider the mackerel as an example of this type. The body is compressed (B), torpedo-shaped (A), and entirely smooth. The most important organ of locomotion is the caudal fin. Power- ful strokes of the tail caused by a wavelike motion of the entire body (C), drives the fish forward with great speed. As organs of equilibrium we find the dorsal and anal fins and frequently also the ventrals. The pectoral fins and partly also the ventrals per- Ficurs 2.—¥our different types of adaptations to movement in water. First type, the most perfect type. Torpedo-shaped body with caudal fin as propulsive organ; A and B, mackerel seen from the side and from the front; C, movements of the fish while swimming. Second type: Plump, broad body, extremities as organs of locomotion; D, Plesiosaurus, from the upper Cretaceous; EH, recent sea turtle. Third type: Snakelike form, the entire body serves as organ of locomotion; F, lamprey; G, eel. Fourth type: The tadpole type, the least efficient form; H, tadpole from above and from the side, form the function of steering. Thanks to all these highly developed adaptations the nectonic, that is the free-swimming, fishes, are the most perfect swimmers we know, moving in all directions with an astounding elegance and ease. Almost the same type of adapta- tions are also found among the recent whales and the extinct Ichthyosaurs. The second type, which can best be compared with a rowboat, is practically unknown among fishes, but is frequently seen in marine reptiles (fig. 2, D, E) and diving birds. It is less perfect. In this HOW THE FISHES LEARNED TO SWIM—HEINTZ 297 case the anterior, the anterior and posterior, or more rarely the pos- terior extremities alone serve in the capacity of oars. They force the short and plump body through the water by powerful strokes, which may perhaps best be compared with the wing strokes of a bird. These forms are as a rule without special organs of equilib- rium or for steering purposes, as the extremities alone serve in all three capacities, that is both for propulsion, balancing, and steering of the body. In some cases, however, the posterior extremities or the tail may serve as a lateral rudder. As the best examples of this type one might mention the sea-turtles (E), the extinct large presio- saurs, and the penguins. The third type must be regarded as even less adapted to swimming. It is the snakelike type (fig. 2, F, G). The animal swims by means of a wavelike motion of the entire body. As balancing organs there are as a rule more or less well-developed median fins. Special organs for steering are usually absent, as the very flexible body takes care of the steering without any special fins. As examples of this type, one can mention the recent cyclostomes or lampreys (F), eels, and a number of other fishes. Many of the recent or extinct amphibians and reptiles also approach this type more or less closely. The fourth group is of a more distinct type. It has, so far as 1 know, not previously been separately defined. In its purest form it is not found either among adult fishes, amphibians, or reptiles, but we encounter it among the larvae of tunicates and amphibians. It is best represented by the tadpole (fig.2,H). The large, somewhat flat- tened, round “ cephalothorax ” (head and anterior part of the body) is without any indication of fins or any other appendages or organs of equilibrium. The tail is strongly compressed, fairly long, with a slightly thickened central core and wide, finlike rims above and below. The tail of the tadpole combines in itself all the three func- tions of locomotion: Propulsion, balancing, and steering. The heavy and clumsy “ cephalothorax ” participates only quite passively in the swimming. Perhaps it may have some function as a gliding plane. Anybody who has seen a tadpole will know that it cannot be considered among the good swimmers. Their adaptations to swim- ming are very imperfect, and we also see that they spend the greatest part of their time resting upon the bottom. But as soon as the pos- terior extremities develop and start to grow, the tadpole begins using them as organs of equilibrium and steering, and the swimming then immediately becomes much more efficient. The tadpole shape with a large head and anterior part of the body (cephalothorax) and a thin, flat tail is not very rare among bottom fishes, but they then Ne have paired and Saeed fins to help 111666—35——16 228 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 them keep their balance and to steer the body; these fishes are there- fore better adapted to swimming than are the young tadpoles. After thus having described the four most important types of adaptations to swimming, we will now consider the modifications of the various old Paleozoic fishes and fishlike forms and try to deter- mine to which of these four types their various representatives have belonged. We will start with the first class, that of the Ostracoderms, which is divided into two subclasses—Cephalaspidomorphi and Ptera- spidomorphi (fig. 1). The Cephalaspidomorphi are known from the Upper Silurian and throughout the Devonian. And we can here differentiate two sharply defined orders; the Osteostraci and the Anaspida. The Osteostraci, which are particularly well known thanks to the recent investigations by Stensié, begin to appear in the Upper Silurian, in which they are represented by some curious flat forms shown in the upper left of our figure 3. This picture shows the so-called Tremataspis from the Upper Silurian of Estonia. The head and anterior parts of the body are covered by a con- tinuous shell. On the dorsal side we find two close-set eyes (fig. 3) with a pineal organ between them and a single nostril in front. At the sides of the shell there are some peculiar sense organs, which Stensié interprets as electric organs. On the ventral side (fig. 3) there is a large opening anteriorly, the so-called mouth- gill opening or oralo-branchial aperture, which is covered only by smaller plates. In this area we find the mouth anteriorly and the gill-openings posteriorly on the sides. The tail is small and thin, covered with large scales, and distinctly triangular in cross-section (fig. 3). The flat belly forms the underside of the triangle. Where the sides join there is a peculiar comblike row of scales forming three longitudinal fringes. These rows of scales are prob- ably the first indications of the medio-dorsal and lateral fin folds. The caudal fin itself is comparatively small, heterocercal, that is with the upper lobe larger than the lower, and is covered with scales. How then has this creature been able to move through the water? A glance at the reconstruction of this form is sufficient to show a striking similarity in the shape of Tremataspis and that of a tadpole. Both have a plump, rounded cephalothorax and a thin rather flat tail. Both are without paired fins and have no well- developed organs of equilibrium. We can consequently say with certainty that 7remataspis was a bottom form, swimming only poorly and uncertainly. Its organs of propulsion, balance, and steering are, as in the case of the tadpole, all represented only by the tail and the posterior part of the trunk. But it is nevertheless HOW THE FISHES LEARNED TO SWIM—HEINTZ 229 more specialized than in the tadpole. In 7remataspis there are three conspicuous longitudinal folds which help to maintain equi- librium and a striking heterocercal tail increasing the effectiveness of the forward propulsion. Ord. Osteostraci. Boreaspis. ¢ is. a Hoelasp Cephalaspis.- Figure 3.—Different representatives of the order Osteostraci (after Patten and Stensi6). Tremataspis from Estonia; from below, above, and cross-section of the body and of the tail. Kiaeraspis from Spitzbergen; cephalothorax from below, above, from the side, and posterior part in cross-section. Cephalaspis from England; from above, from the side, head from below, and in frontal view. Boreaspis from Spitzbergen. Hoeleaspis from Spitzbergen. Long-spined Cephalaspis from Spitzbergen. If we consider the later osteostracs such as Kiaraspis (fig. 3), we will see that evolution has progressed further. In this form, the cephalothorax is more specialized and divided into a section of the head and a section of the body. On the boundary between these two sections some distinct flat spines have been developed. The 230 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 structure of the tail was probably similar to that in Tremataspis but broader. In this form we, therefore, have an addition to the three longitudinal folds on the posterior part of the body in the form of the two flat projections on the sides of the cephalothorax, which serve as organs of equilibrium and at the same time increase the surface of the cephalothorax and thus function also as an accessory gliding surface. The most highly specialized forms of the Osteostraci are the Cephalaspids (fig. 3) which are still better adapted to swimming. In these forms, practically only the head is covered by a hard shell, while the entire rest of the body has scales only and is therefore movable. The tail is large and the median and lateral folds are more strongly developed. In addition, most of these forms have a distinctly developed dorsal fin. The projections on the side of the head already indicated in the earlier forms have become larger—some even very large. On the posterior part of the head a third median dorsal projection is dis- tinctly developed and may reach a large size in some species. We finally see in the bights between the lateral projections two peculiar lobe-shaped organs of the nature of paired, movable pectoral fins. All this seemed to indicate that the Cephalaspids were considerably better swimmers than Zvremataspis, and they are no longer so tadpolelike but approach the true fish type more closely. The tail is still the most important organ of propulsion, and the lateral and median folds, the dorsal fin on the body, and the lateral and median projections on the head are excellent organs of equilibrium. We finally have the paired pectoral fins as effective organs of swimming. Even if Cephalaspis was a typical bottom form, it could certainly swim as well as, for instance, one of our recent sculpins. We also see very clearly how the different Osteostraci became grad- ually better and better adapted to swimming. Parallel with this development a gradual reduction in the thickness of the external skeleton also took place. In the oldest form such as 7’remataspis the shell is thicker, in the younger forms it is more and more strongly reduced as particularly pointed out by Stensio. With this reduction the fish becomes lighter and in consequence better fitted for swim- ming. The second group of the Cephalaspidomorphi (fig. 1) are the so-called Anaspids, which first became really known after the thorough investigation of recent finds published by Kiaer. The Anaspids (fig. 4) are only known with certainty from the upper Silurian, but some uncertain remains have also been described from the Upper Devonian. They have a strongly compressed torpedo- shaped body with a pointed snout and a powerful so-called hypocer- HOW THE FISHES LEARNED TO SWIM—HEINTZ Dak cal tail, that is, the lower lobe of the tail is more strongly developed than the upper. The head and trunk are covered with fine, thin scales. Everything therefore indicates that we have a relatively good swimmer, a highly specialized form. The adaptations of the Anaspids to swimming are nevertheless not as perfect as in the recent free-swimming species. The organs of equilibrium in the Anaspids consist of only a row of spinelike fulcra scales along the back and a relatively strong anal fin. There are, in addition, on both sides of the body immediately behind the gill-opening two pe- culiar immovable spines. They must certainly have corresponded to the paired fins in other fishes, but it is doubtful whether they could have any significant function as organs of steering or equilib- rium as they were much too thin and narrow. The lack of organs Ord. Anaspida. a ae Wy " AWS WN Ficurp 4.—Two representatives of the order Anaspida: A, Pterolepis; B, Remigolepis. Cross-section of the body and the anal fin in anterior view (after Kiaer). of equilibrium is a very peculiar phenomenon. We know that all torpedo-shaped free-swimming fishes are in a state of unstable equilibrium in water, as the lower part of the body (with the ab- dominal cavity) is lighter than the solid muscular back. We see this most distinctly in sick or dead fishes which always swim or float with the side or the belly up. In a living condition they main- tain their upright position in the water by motions of the tail, the unpaired and chiefly the paired fins. It must have been difficult for the Anaspids to maintain their equilibrium without considerably developed fins. Perhaps the peculiar hypocercal tail with the down- ward-directed thick body axis helped them in keeping the right position in the water. In spite of all this, however, we must still consider the Anaspids as having been comparatively good swimmers, even if their adaptations to swimming were not as perfect as we find them in the youngest true fishes. 232 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 The second large subclass of the Ostracoderms (fig. 1), the Pter- aspidomorphi, have a more peculiar build. Some of the oldest forms, which are known from as far back as the Ordovician, are the so-called Thelodonti (fig. 5). The entire body including head, tail, and fins, is evenly covered with small, close-set scales. The head and the fore- most part of the body, the “ cephalothorax ”, is broad and flat; the hindmost part, on the other hand, is narrow and the tail probably Ord. Thelodonti I'icuRp 5.—Two representatives of the order Thelodonti (after Traquair). A, Lanarkia from Scotland; B, Thelodus from Scotland. hypocercal. The postero-lateral corners of the cephalothorax are produced into a pair of flat, brimlike fins. On the posterior part we find a small anal and dorsal fin. In their shape the Thelodonti re- mind one very closely of the oldest Osteostraci which we have just described, and also of the tadpole. We have certainly to deal with bottom forms, which were swimming around like tadpoles even though they had organs of equilibrium in the form of lateral flaps and also a median fin. HOW THE FISHES LEARNED TO SWIM—HEINTZ 233 More interesting is the development of the second group of the Pteraspidomorphi, the so-called Heterostraci, which are known from the upper Silurian to the Devonian (fig. 1). Sub. 0rd. Cyathaspida. l'igurp 6.—Different representatives of the suborder Cyathaspida (after Kiaer). A, Anglaspis from Spitzbergen; from the side, from above, and cross-section of anterior part of body and of the tail. B, Poraspis from Spitzbergen; from the side, and cross- section of the shields. C, Ctenaspis from Spitzbergen; head shields from above, and in frontal view. D, Cyathaspis, cephalothorax from above. The oldest (Cyathaspids), which have been thoroughly described by Kiaer, resemble in their shape the oldest Osteostraci (fig. 6). The head and the foremost part of the body are also covered by a shell, which, however, does not consist of a continuous armature, as in Z'remataspis, but of two large plates, one dorsal and one ventral. 234 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 The form of the posterior part of the trunk and the tail are not as well known, as these parts have been found completely preserved only in one single species from Spitsbergen. The posterior part of the trunk and the tail were probably considerably shorter and thicker than in 7’remataspis, and covered by very solid, thick scales. ‘The structure of the cephalothoracic armature varies considerably in the different forms. In some it is more oval and rather flat (fig. 6, A, B), in others more elongate and almost cylindrical with a circular cross- section. How were these forms able to move through the water? They certainly had no paired fins nor any unpaired ones and they also lacked any distinct spines. The only movable part of the animal, the posterior trunk and tail, were covered by exceptionally solid and thick scales, which prevented the possibility of any strong and lively movement. ‘Thus we see that the primitive Cyathaspids had neither any organ of equilibrium nor steering organs and that fur- thermore their organ of propulsion, the hind part of the body and the tail, were also less flexible and movable than in tadpoles or the oldest Osteostraci. From this we can conclude that the Cyathaspids were very poor swimmers and spent their time chiefly on the bottom, perhaps partly buried in sand and mud. The next step in the adaption of the Heterostraci is found in the large group of the true Pteraspids (fig. 7). They are all flatter, more conspicuously compressed dorso-ventrally. The dorsal shield, which was undivided in the Cyathaspids, has been split into several separate plates. Of greater interest, however, is the development of the different spines and projections. To begin with, we find distinct lateral projections on each side behind the gill-opening (fig. 7, A 38). These projections vary greatly in different forms, as one may see from the figure. In some it assumed almost fantastic dimensions (fig. 7, D, E), in others it was almost completely obliterated (fig. 7, C). As in the case of the similar projections in Cephalaspids it is evident that these spinelike parts in the Pteraspids served primarily as organs of equilibrium, but secondarily also, and then particularly in the forms with very large spines, as a gliding organ. Apart from these two symmetrical lateral spines we find also a median dorsal spine de- veloped in most of the Pteraspids. This dorsal spine is located at the posterior end of the dorsal shield and is directed obl.quely up- ward and backward (fig. 7, A, B, C, D). This spine corresponds entirely to the comblike development of the posterior part of the cephalic shield in the Cephalaspids and must assuredly have served as an organ of equilibrium. HOW THE FISHES LEARNED TO SWIM—HEINTZ Sub Ord.Pteraspida «& SubOrd Psammosteida. Ficurn 7.—Different representatives of the suborders Pteraspida and Psammosteida (after Kiaer, Bryant, Gross, Lerich, and Traquair). A, a small Pteraspis from Spitzbergen ; from above, below, and from the side. B, Protaspis, a form from America; seen from above. C, Pteraspis from Germany. D, Pteraspis from France. E, Dyrcaspis, a new form from Spitzbergen. F, Drepanaspis from Germany. 236 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 Paired fins have not been found in the Pteraspids. The tail and the posterior part of the trunk was, on the other hand, more flexible and much more slender than in the Cyathaspids (fig. 6, A). The large, thick Cyathaspid scales have been spht into numerous small rhombic scales, which also cover the large hypocercal caudal fin (fig. 7, A, B, E). The cross-section of the tail is a more or less rounded oval, not triangular as in the Cephalaspids (fig. 3) and is without any indications of lateral folds. Generally speaking, the Pteraspids must therefore have been bottom forms, which by means of powerful tail strokes lifted themselves from the bottom to glide through the water on their large, wide, lateral spines in the manner of a modern gliding plane. Parallel with this development, again corresponding entirely to conditions among the Cephalaspids, we find also that a strong reduction in the thickness of the shields has taken place. In the youngest Pteraspids (from the Lower Devonian) the dermal arma- ture was paper-thin and very light. We thus see that the Cyathas- pid-Pteraspid line of evolution in its adaptations to swimming has not reached as far as the Tremataspid-Cephalaspid line which we first described. The latter gradually acquired both organs of equi- librium in the form of spines and lateral and median skin folds, and steering organs in the form of movable paired fins. The Pteraspids did not get further than to the development of lateral gliding spines. No indication of paired fins or lateral fin folds is known in th's group. Another line consisting of the Heterostraci, the Drepanaspids and Psammosteids (fig. 7, F) has followed another path of evolution and remain typical flat bottom forms with short tail, weakly developed lateral spines and no dorso-median projections. We know forms ot this general character from the Lower to the Upper Devonian. Some of them reach a considerable size, over 1 meter in length. The recent Cyclostomes, comprising the lampreys and hagfishes, are, as already previously mentioned, closely related to the fossil Ostracoderms. They also have not advanced very far in their adaptation to swimming. They are entirely snakelike (fig. 2, F). winding their way through the water. A median fin fold runs along the posterior part of the back around the tip of the tail and a distance forward along the ventral side. Neither do we find in the Cyclostomes any trace of paired fins. They have special organs of locomotion or of steering, and their organs of equilibrium are only represented by the median fin fold. We thus see that the primitive fishlike forms of the order Agnathii (fig. 1) have not attained any specially high adaptation to swimming. Only one single family, the Cephalaspids, had distinctly differenti- ated organs of steering, equilibrium, and propulsion, while the body, HOW THE FISHES LEARNED TO SWIM—HEINTZ 237 on the other hand, was not torpedo-shaped but entirely flat, of a typ- ically benthonic character. A second group, the Anaspids, had tor- pedo-shaped bodies, but were, on the other hand, without any highly developed organs of steering and equilibrium. When we now turn our attention to the class Pisces, or the true fishes (fig. 1), then it is particularly the so-called Placoderms which are of interest. With the Elasmobranchs,’ they belong to the oldest- known true fishes, and their first remains are found at the transition from the Silurian to the Devonian. These oldest forms belong to Un. Kl. Arthrodira. Coccosteus. licurE 8.—Different Arthrodira (after Broili and Heintz). A, Acanthaspis from Spitz- bergen; (1) from above, (2) from the side, (38) body shield seen from the front, (4) cross-section of a lateral spine and the side of the body shield. B, Acanthaspis from Germany; with completely preserved posterior part of trunk. C and D, two different types of body shields of Acanthaspids from Spitzbergen. EH. Coccosteus, an Arthrodire from the Middle Devonian; internal skeleton strongly calcifid. the subclass Arthrodira and the order Acanthaspida, which has be- come particularly well known through the discoveries in the Lower Devonian of Spitzbergen. Everything seems to indicate that this order must be regarded as the central systematic unit among the Arthrodires, from which the different other families have sprung. The head and the foremost part of the body of the Acanthaspids (fig. 8, A, B) were covered by a solid shield as in all other Arthrodira. But whereas we find the shield of the head and body in the Ostraco- derms united into a single shell, the cephalothorax, the shields of the 8According to Stensid’s investigations, the Placoderms must be regarded as belonging to the Elasmobranchs. 238 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 Arthrodira are divided into two separate parts: the head shield and the body shield, which are movable and connected with each other by a double joint, which permits a more or less free movement up or down of the head in relation to the body. The head in Acanthaspis is flat, the small eyes are situated laterally far forward in the skull. Immediately in advance of them are the nostrils. The body shield in the Acanthaspids is rather low (fig. 8, A 2, 3; fig. 9, A), entirely flat below and somewhat arched above, with a sharp bend along the median line. Particularly characteristic of the Acan- thaspids, however, are the strongly developed immovable lateral spines, which are located on both sides of the anterior part of the body shield, behind the gill opening (fig. 8, A, B). If we view the an- terior portion of the shield and the spines in cross-section it is not difficult to understand that we are here dealing with a genuine fold of the skin (fig. 8, A 4). It is therefore entirely natural that these spines should be regarded as homologous with the pectoral fins of other fishes. The spines are moreover not entirely horizontal, but their anterior edge is somewhat lower than their posterior edge, that is, they slant a little forward. The posterior part of the trunk and the tail in the Acanthaspids was covered with rather solid scales as we can see quite distinctly from an almost complete specimen of Acanthaspis found in the German Lower Devonion and described by Broili (fig. 8, B). The same specimen also shows us that the Acanthaspids were without pelvic fins, and only had weakly developed medio-dorsal fins or spines. It is particularly noticeable that the caudal fin also seems to be lacking, as the body apparently simply tapers to a point. There can be no doubt that the Acanthaspids were typical bottom forms which swam very poorly. While swimming they used the posterior part of their trunk and the tail as organs of propulsion. The organs of equilibrium can be seen in their powerful spines and in their dorsal fins. Special steering organs in the form of movable paired fins are entirely absent. The spines probably not only served as organs of equilibrium but also as gliding organs in a similar manner as in the Cephalaspids and Pteraspids (figs. 2 and 7). Acanthaspis would rise from the bottom by powerful strokes of its tail, descend- ing again more slowly, gliding on its spines. The Acanthaspids disappear completely in the Middle Devonian, where they are replaced by a great number of other Arthrodirans showing the most diverse adaptations. Some adapted themselves more and more completely to a bottom mode of hfe, developing a rather flat head and body shield. Others, on the other hand, be- came free swimmers. A very well-known form from the Middle Devonian, Coccosteus (fig. 8, E; fig. 9, B), is fairly close to the Acanthaspids, but shows distinct adaptations to more efficient swim- HOW THE FISHES LEARNED TO SWIM—HEINTZ 939 ming. The body is much higher, even though the ventral shield is still rather flat (fig. 9, B). The large spines are strongly reduced and can no longer serve as effective gliding surfaces. The posterior part of the trunk and the tail are, on the other hand, more strongly developed. The scales are entirely reduced and a solid calcified internal skeleton has been developed (fig. 9, E). From its structure we can conclude that the tail was still pointed and tapering, with- out special caudal fins, but Coccosteus, on the other hand, had a strong dorsal fin, an anal fin, and, besides, a set of pelvic ventral fins. In other words, Coccosteus has already developed, in addition Un.Kl. Arthrodira Ficurb 9.—Gradual evolution of Arthrodira from pure bottom forms to free-swimming representatives. A, Acanthaspis. B, Coccosteus. ©, Dinichthys. D and BE, flat, free- swimming forms from German Upper Devcnian. F, Solenosteus, an Upper Devonian form in which the joint between the head and body has disappeared. (After Gross and Heintz.) to the organs of equilibrium in the form of small lateral spines (ho- mologous with the pictoral fins) and median fins, an efficient steering apparatus in the form of paired ventrals. Its entire shape also sug- gests that it must have been a better swimmer than Acanthaspis, in spite of the fact that it was still a characteristically bottom form. The further evolution of the swimming Arthrodira goes in the di- rection of a more laterally compressed body and narrower ventral shield, and a more powerful development of the tail (fig. 9, A-E). Parallel with all these changes, corresponding entirely to what took place in the Ostracoderms, we also find a reduction of the thickness of the shield which in the youngest Upper Devonian forms has become paper-thin. 240 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 The last step in the adaptation to free-swimming is seen in a group from the Upper Devonian, in which the connecting joint between the head and body otherwise so characteristic of the Arthrodira has dis- appeared, and the head and body shields have become fused (fig. 9, F). The peculiar connection between head and body in the Arthrodira is practically unknown among fishes as it can only have served to interfere with the function of swimming. In the bottom- Ficurp 10.—A representative of the subclass Antiarchi (after Traquair). Pterichtys from the English Middle Devonian: Upper left, from above; upper right, from below ; and lower figure, from the side. - living Arthrodira the head-body joint has been retained until the last Upper Devonian form, but in the more free-swimming repre- sentatives the head loses its separate mobility. Thus we see how this group also, starting from typical bottom forms, gradually conquered the ocean and learned to swim. The second group of the Placoderms (fig. 1) the so-called Antiarchi (fig. 10) are undoubtedly among the most peculiar beings which have ever inhabited the sea. In their strongly encased head and trunk they remind one a good deal of the Arthrodira. The head shield in these also is connected with the trunk shield through a joint (fig. 10). HOW THE FISHES LEARNED TO SWIM—-HEINTZ QA We have here again a group of typical bottom forms, with a flat ventral shield and a strongly arched dorsal armature. The most peculiar feature is the development of the pectoral fins, which are modified into strongly reinforced spines (fig. 10). By means of a very complicated joint these spines are movably connected with the body shield. It is very tempting to regard these organs as a kind of oars by means of which the animals could swim through the water. This interpretation is rather improbable, however, as the connecting joint between the body and the spines is much too complex to permit any rapid motion, and the oars themselves are furthermore too thick and narrow and cannot be said to be in any manner an efficient type of swimming organ. On the other hand, they may very well have served as steering organs. The posterior part of the trunk and the tail were very short in the oldest form, and covered by scales. In the younger ones they were considerably longer and more slender and the scales were completely reduced. No Antiarchi show any perfect adaptation to free swimming. They all remained benthonic and only varied in their ability to lift themselves from the bottom. T shall not attempt any detailed discussion of the two largest groups of fishes, the Elasmobranchs and the Teleostomes, which are the dominant forms in recent times. The Elasmobranchs are known as far back as from the upper Silurian, the first Crossopterygii were certainly from the Lower Devonian. Even the oldest Teleostomes could in all probability swim relatively efficiently (fig. 11, A, D). The body was more or less oblong, and they had a large caudal fin as well as median and paired fins. I shall, however, not discuss their structure any further but shall proceed to another problem. It is commonly acknowledged that the original or so-called primary form in fishes was more or Jess torpedolike, a form which is very well adapted for free-swimming in the water. The fishes have subse- quently. also adapted themselves, secondarily however, to other modes of life and have correspondingly modified their shape. Thus some of them have become flying fishes, others have changed to a bottom mode of life and some have become deep-sea fishes. Conditions are fairly clear insofar as we consider only the recent and the higher fossil Teleostomes. In these cases we can as a rule show that for instance the bottom forms have always been derived from free- swimming ancestors. On the other hand, we have in the preceding considered a series of the old Paleozoic fishes and fishlike forms and know that they began from a bottom existence and only gradually learned to swim. We have seen that of a great number of Ostracoderms and Placo- derms perhaps only a few, and then as a rule the youngest ones, can really be regarded as having been nectonic forms, that is, forms 242 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 which may spend their entire lives swimming around in the water without of necessity having to resort to the bottom. Shall we now have to consider all these old Paleozoic forms as having been only secondarily benthonic? Do we really have to as- sume that they were derived from earlier free-swimming ancestors? To me the opposite thought seems much more natural, namely, that the oldest fishlike forms and fishes were primarily bottom-living. We know very little about the ancestral forms of the vertebrates. But we may take for granted that they evolved in water. It is then also most natural to assume that the earliest, most primitive forms, lived on the bottom and had not yet: specialized sufficiently to be able to swim. If the oldest vertebrates were bottom-living or perhaps even burrowing forms, they must have learned to swim just as they later had to learn to crawl, walk, run, and finally fly. In my opinion the oldest known vertebrates, fishlike forms, and fishes, had not yet learned to swim, and we can in them observe the gradual transition from bottom-living to free-swimming forms. The clumsy forms with a large cephalothorax and a short thin tail, with- out organs of steering and balancing, could only move rather helplessly through the water and could scarcely lift themselves from the bottom (figs. 8, 5, 6). The further evolution went in the di- rection of the development of organs of equilibrium and of gliding surfaces in the form of more or less strongly developed spines or projections (fig. 3; fig. 7, A-E; fig. 8, A-D). The next step was the formation of effective steering organs in the form of movable paired fins (fig. 3, fig. 8, E). When all these technical difficulties had been overcome, the further modifications continued only in the direction of a more perfect adaptation of the entire body and of each separate organ to the function of swimming. First of all, a gradual reduction of the heavy and thick external armature or scales took place, thereafter a modification in the shape of the body, and finally, a gradual perfection of the most important organ of propulsion, the caudal fin. Parallel with these changes the inner skeleton also grew stronger and came to form a strong support for the greatly developed swim- ming musculation (fig. 12). We have seen the first step in this evolutionary series in the Ostracoderms and Placoderms. The well known evolutionary series of the Teleostomes show the subsequent steps very clearly (figs. 1, 11, and 12). The oldest Devonian Crossopterygian (fig. 11, A; fig. 12, A) still have a comparatively plump body, and their large heads are covered by thick bony plates, their bodies by heavy scales. Their paired fins are brush-shaped and cannot be closely applied to the body, which fact serves to prevent very rapid swimming. Their heterocercal tail has a strong, scaly axis. They are fair but not yet HOW THE FISHES LEARNED TO SWIM—HEINTZ Avd, Teleostomi. ———= = = =: S eee, Ss > SS SS SE aed YL, Hy] L/ IANS cine ee le. FOP a. § “\e= c gw Ss Chondrostei. Neat ) Ss Sa q Crossopterygii. Roa Figure 11.—Gradual evolution of different Teleostomes in the direction of better and bet- ter adaptations to swimming. A, a Crossopterygii (Holoptychius) from the Devonian ; B, a Dipnoi (Dipterus) from the Devonian; OC, a Chondrostei (Amblypterus) from the Permian; D, a Holostei (Lepidotus) from the Jurassic; H, a Teleostei, a recent mackerel. (Chiefly after Traquair and Woodward.) very good swimmers and have in all probability preferred to live near the bottom. Their inner skeleton is weakly ossified. The same is also true of the Dipnoi (fig. 11, B, C, D, E; fig. 12, B, C, and D) 111666—35——17 243 244 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 The Acanopterygii are already much better adapted to free swim- ming by the structure of their paired fins, which can be closely ap- plied to the body. But in some of the oldest Chondrostei (fig. 11, C; Iieurp 12.—Gradual evolution of ossification of the internal skeleton in different Teleostomi; A, in a Crossopterygii (Tuursius) from the Devonian; B, in a Chrondro- stei (Palaeoniscus) from the Permian ; C, in a Holostei (Dapedius) from the Jurassic; D, in a Teleostei (Hoplopteryr) from the Tertiary. (After Woodward.) fig. 12, B) which reach their greatest abundance in the younger Paleozoic, the inner skeleton is still weakly ossified and the body covered with thick, heavy, ganoid scales, and the tail heterocercal with a long, scaly axis running out into the upper lobe. HOW THE FISHES LEARNED TO SWIM—HEINTZ Q45 The next group, the Holostei (fig. 11, D; fig. 12, C), which abound in the Mesozoic, have still to a large extent preserved their ganoid scales, but the internal skeleton is much more strongly ossified and the tail has become almost entirely homocercal (evenlobed) as the scale-covered body axis in the upper lobe is strongly reduced. Finally the recent Teleostei (fig. 11, E; fig. 12, D) have developed a completely ossified skeleton, and their scales are very thin and light, sometimes even completely absent, and their tails have become entirely homocercal. In these forms we therefore have the most perfect type of swimmers (fig. 2, A). The evolutionary series here described is, of course, entirely dia- grammatic. One cannot, of course, consider, for instance, the Ostra- coderms or Placoderms as real and direct ancestors of the younger fishes. But, as in numerous other series of comparable though not directly related evolutionary types, this series shows how the evolution in all probability has progressed, and how the different fundamental types have superseded each other. In general the evolution has proceeded parallel and independently within numerous differ- ent groups. 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With this man-made condition and long ante- dating it are those natural wonders, its remarkable flora and fauna. In no other country are there found in so small an area such inter- esting and attractive mammals, reptiles (including snakes and croco- diles), birds, fishes, and insects. Botanically, also, the island is of outstanding importance, with a wealth of exotic plants, particularly the trees and shrubs, many of them bearing richly colored flowers, valuable fruits, and other useful products. Geographically, the island is situated almost directly south of the Indian peninsula about 6° north of the Equator, with an extreme length of 270 miles and a greatest width of 187 miles. The country presents an almost unbroken covering of forests interspersed with over a thousand large and small artificial lakes, a central mountain zone, with a few peaks reaching 7,000 feet, and a dozen or more short but important rivers. Despite its large proportion of unsettled jungle and forest, there are many good motor roads giving access to all parts of the island. Sinhalese birds number 371 species, of which about 52 are indige- nous. As a modification of this statement it must be remembered that about two-thirds of the avian species found in Ceylon are known to breed or to have bred there, so that these may be regarded as resi- dents. As Wait says, “ Not counting about 20 species which may be classed as oceanic wanderers, roughly 125 forms, one-third of the total bird species, are wholly migrant. About 40 of these, however, have been recorded only on a few occasions, and less than one-half of the migrant total are really common and familiar birds. The percentage of migrants is far greater among Ceylon water birds than among the land species, while the general ratio of migrants to resi- dents is far lower in this tropical island than in temperate regions.” 247 248 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 The roster of Ceylonese birds includes numerous owls and hawks, and several eagles, although the last are of the smaller varieties and are rather rare. There is also a beautiful, distinct subspecies of the jungle-fowl. Rather abundant are the species and races of wild pigeons, parrakeets, sunbirds, flycatchers, kingfishers, and orioles, most of them dressed in brilliant plumage. One might also mention crows (two species), toucans, the edible swift, partridge, snipe, and quail. Perhaps the most noteworthy of the avian fauna are the water birds and waders, among them many ducks, teal, flamingos, storks, egrets, ibises, herons, and spoonbills. Bird protection through legislation and the fact that the majority of the inhabitants are Buddhists account for the great number, vari- ety, and persistence of the avian population. Some of the birds peculiar to the country* are of great interest and call for better colored portraits and plumage descriptions than this paper can furnish. One of these is a beautiful trogon (Har- pactes fasciatus (Pennant)). It may be regarded as a subspecies of the bird found in South India where, as in Ceylon, it is seen only in thick and usually high forest. These birds are found in pairs; they are insectivorous, hawking their prey in the air, and their call note is a peculiar whistle. The accompanying plate (pl. 1, fig. 1) gives only a faint idea of this bird’s brilliant plumage. Another notable species is the small Ceylonese hornbill (7ockus griseus gingalensis (Shaw) ), fairly common throughout the bush of the low country, where it is seen in the tops of the trees. Its call closely resembles a human laugh repeated with increasing harshness and frequency. Its food is fruit and large insects. It breeds from April to August and, following the rule of the genus, the female is walled up by means of a plaster of droppings in the nest, a tree cavity, by the male and is fed by him during the incubation period through a narrow opening in the covered retreat. The races of babblers (most inappropriate name for birds that, whatever notes they emit, never “ babble”) are well represented in Ceylon, some of them being indigenous species. The brown-capped babbler (Pellorneum fuscicapillum (Blyth) ) is a shy, skulking bird of the forest that builds a domed nest well hidden on the ground and whose call is a sharp whistle. The common babbler, a friendly bird, is nearly always found in flocks of from 5 to 7 and goes in Cey- lon by the name of the “ seven sisters.” This company is probably made up of members of several families who flock together. I do not agree with Miss Kershaw as to the notes of Z’urdoides griseus striatus (seven sisters). My experience of this very common bird 1See Coloured Plates of the Birds of Ceylon, by G. M. Henry, Ceylon Government Printing Press, Colombo, 1927-30. BIRDS OF CEYLON—Wwoop 249 is that instead of being a “ noisy bird, possessing a variety of scream- ing notes ”, these babblers have rather a subdued series of tinkling or piping calls that are rather agreeable than otherwise; a gentle, reedy note, quickly repeated, one might say. The scimitar babbler (Pomatorhinus horsfieldi melanurus) is well worth a brief mention. I have heard this bird in the Kandyan hills repeating (probably the male) something like this in deep, distinct tones—rather low, trilling, and liquid—* goo-goo-00 goo-goo-goo ” about six times, much like the coppersmith in rate, except that its notes can be counted, whereas the coppersmith calls are too fast for numeration. Miss Kershaw says that when heard in early morning the male says “ what-a-good boy, what-a-good-boy.” The female ends her notes with “ poor chick.” Legge says the male call is a quick “ wok-wok-ek-ek-wok ” ; the female a shorter call. More beautiful than the foregoing, and peculiar to the island, is the black-capped bulbul (Pyenonotus melanicterus (Gmelin) ), both sexes with bright orange markings. This species feeds largely on berries, has a length of 6.5 inches, and is everywhere seen. Another bulbul, and there are several of these species suggesting but having no real relation to the European nightingale, is the yellow-eared bulbul (Kelaartia penicillata (Blyth) ), a rather tame bird frequent- ing inhabited areas and feeding mostly on fruits. It is slightly larger than the black-capped bulbul. A curious representative of the drongos is the king-crow (Dicrurus coerulescens leucopygialis (Blyth)), a pugnacious, 9.5-inch species which rules the roost about inhabited houses and gardens and keeps the bird population, large and small, in regimented order. He hates and chases owls and woodpeckers and is something of a mimic. This white-vented drongo is in some districts called Kawudu-panikkiya or the “ crows’ barber ”; in others, Kaputu-bena, the “ crows’ nephew.” It is often seen chasing both gray and black crows, snatching feath- ers out of their plumage, especially from the head. The natives explain this vendetta by saying that in a previous birth the drongo was a barber and the crow a customer who failed to pay. In this incarnation he is not only being punished for his dishonesty, but the drongo is permitted to dun him for the arrears. The second synonym is explained by the fact that the drongo is so cunning that even his crafty uncle, the crow, was cheated by him. According to the folk- tale, the drongo challenged the crow to a high-flying contest, the challenge being accepted on condition that each should carry a cer- tain-sized bag filled with any material he chose, and that the winner should, as his reward, be at liberty to knock the loser on the head. The crow craftily chose cotton, the drongo, weatherwise, filled his bag with salt. They had not soared far before it began to rain in 250 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 torrents; the crow’s bag absorbed and retained the water and, of course, got continually heavier, the drongo’s load became continually lighter owing to the washing away of the salt, and before long he had nothing to carry. The drongo won, and has ever since exercised his privilege of pecking at the crow’s head. The racket-tailed drongo (Dissemurus paradiseus ceylonensis Sharpe) is much more striking (see pl. 3, fig. 1) in appearance than the foregoing, although by no means more interesting in its habits. The genus that includes the barbets has always been of great interest tome. These remote allies of our woodpeckers excavate a nesting hole in some soft wood or decayed tree, often near a human habitation, and make no effort to conceal themselves or their works. The Indian crimson-breasted barbet (Xantholaema haemacephala indica) is rep- resented on the island by the small Ceylon barbet. The local name of this very common bird is the coppersmith, and whoever has lstened to its pneumatic-hammer call (so rapid are the strokes that they cannot be counted) will consider it an appropriate title. The Ceylon green barbet (Vhereicerya zeylanicus zeylanicus) is another inter- esting species. At any time of day can be heard the loud call of this bird—“ mo-hawk, mo-hawk ”—3 or 4 times repeated, the accent being alway decidedly on the second syllable. Sometimes the notes will be kept up at short intervals for an hour, thus earning for the bird the (local) title of “brain-fever bird”. The first or introductory notes are sometimes slurred. The kingfisher in one form or other is almost cosmopolitan}; it is found all over the world, from the large laughing jackass of Australia to the pigmy species of South America and elsewhere. Although they generally feed on fish alone, their food sometimes includes large insects, small reptiles and amphibia. The Ceylon species are remark- ably beautiful and possess peculiar habits. If we are to believe the evidence of the drongo’s attitude toward Sinhalese kingfishers, the latter are not guiltless of occasionally stealing the nestlings of other birds. To me the most interesting species is the pied kingfisher of Ceylon and India (Ceryle varia). Instead of darting on its finny prey from the branch of a tree or other perch, this black and white bird flutters over the water, like a kestrel or a hummingbird, watching for fish. I have often observed this curious kingfisher, poised in air, turning his head from side to side searching the water beneath him until, his fish in view, he made a sudden plunge and rose with the catch in his mandibles. Of the lovely parrakeets, both indigenous and migratory, that be- long to the Sinhalese list, one may remark that these birds cannot in Ceylon (or elsewhere, for that matter) be poked, pulled, snared, or smoked out of their arboreal holes without killing or irreparably BIRDS OF CEYLON—WooD PASI injuring them. In vain does one hammer on the tree or shout down the nest aperture. The parrot knows he or she is safe and inacces- sible and simply lies “ doggo”. Wait has well described the native Sinhalese method, an ingenious and humane one, of capturing par- rots, both nestlings and adult birds. It is practically impossible by ordinary means to dislodge these birds from the deep holes in hard- wood trees which they generally choose as a refuge from various enemies, and where they may raise a brood in peace and quiet. The fledglings are generally two, although most Ceylon parrakeets lay three or four eggs to the clutch. As a rule, the hole is too small and too long and deep, lke a woodpecker’s nest, to be reached by any native arm however long and skinny, not to mention the strong, curved beak and needle-pointed claws that are waiting for invaders from above. I have already described elsewhere my adventure on a Pacific island when, with native assistance, I tried to examine the nest of a Polynesian parrot, whose nesting activities had never be- for been described. On that occasion we did not wish or try to cap- ture the mother parrot who was sitting on her two eggs secure from interruption at the bottom of a 4-foot hole in the stump of a tree that was as hard as any oak. There she was, and there she stayed, quite unaffected by any efforts of ours to dislodge her, and we were obliged eventually to hack through the base of the stump before she could be dragged, with some inconvenience to herself, from her hid- ing place. The only damage done was to the Kandavan who, with his big chopping knife, had acted as excavator. He received several deep scratches and one vigorous bite that cost me half a tin of cigarettes. The Sinhalese resort to no such crude methods. When a parrot’s nesting pocket is discovered, the natives keep watch of it, and when, from various signs, the occupants are believed to have arrived at a suitable age for caged life, the Sinhalese boy shins up the tree in a trice and, standing on a nearby branch or simply clasping the trunk of the bole holding the nesthole, dislodges the birds without trouble. It is a triumph of brains over brute force. There is no laborious cutting away of the wall of the nesthole, with its possible danger of injuring or (almost as bad) frightening the birds half to death and thus lessening their value either as human companions or as a commercial commodity. From the native’s neck is suspended a bag filled with dry sand. From this he takes a handful and carefully, a little at a time, pushes it into the hole. The sand falls on the parrots’ backs. They shake it off and trample it under foot. The operation is repeated—remember that time is of no importance to the Sinhalese, who is engaged in a task of his own choosing—until the birds grad- ually elevate themselves to the top of their excavated nest. A prac- 252 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 ticed grasp of the now exposed bird, with perhaps a bite or scratch or two (if the adult bird is at home) and the family are thrust, without the loss of a feather, into an empty sack. It is by this means that the charming little indigenous parrot, Layard’s paroquet (Psittacula calthrapae (Layard)) is captured. It is a beautiful forest and hill species, sometimes found about vil- lages and paddy fields, its eggs being laid in a hole high up in a dead coconut palm or other tall tree. Another lovely little parrot, the common Ceylon loriquet (Coryllis beryllinus (Foster) ) is found in almost any low country jungle or native garden. It has a vora- cious appetite and is fond of drinking the toddy from the pots in which it is being collected—a regular avian toper. The eggs, laid in some natural cavity of a tree, are deposited in a nest made of green leaves. In two of his 555 reincarnations Buddha was a parrot, an honor that conferred upon the genus the power of speech. The Sinhalese have a number of sayings about this interesting order. For example: “When the cat mews the parrot’s 18 languages come to an end.” “Though the cage be made of gold, the parrot prefers a roost in the forest.” “As ungrateful as a parrot”, who may bite his best friend. “This fellow is like a parrot ”—a chatterer or a mere imitator. The red-wattled lapwing is to the Sinhalese the type of watchful- ness and faithfulness to its offspring. At all hours, day and night, when its nest is approached it rises with a shrill cry. It is believed by the natives that the eggs, eaten raw, will drive away sleep and induce watchfulness. It is also asserted by them that the lapwing lies on its back in its nest with its legs upward to keep its eggs from being crushed should the sky fall. Jerdon notes the same belief in South India. A Sinhalese proverb says that “truly pious and revered priests are those who observe their religious vows as assidu- ously as the kirala (lapwing) guards her eggs, the samara (deer) his tail, the father his only son, and the man with but one eye the remaining organ.” In one of the early Buddhistic manuscripts oc- curs the following: “She who has become pure in mind and body observes on poya days the eight rites and every day the five rites as (faithfully as) the kirala guards her eggs and the samara his tail.”—(Nell.) The Ceylon crows, both the common gray variety and the jungle crow, are intelligent thieves, the former with a marked predilection for stray golf balls. These birds have many sayings attributed to them by the Sinhalese. The native name, Kakka kaputa, is inter- preted to mean “ I eat everybody (everything), but nobody eats me.” “A cunning man’s look is like that of a crow.” “There is no place BIRDS OF CEYLON—WoopD 253 that the Moorman [not much liked by the aboriginal Sinhalese] and the crow are not found.” “The crow also said, ‘It is bad to play with bows and arrows.’” As showing his ingratitude, “The pea- cocks gave shelter to a crow who, in return for their hospitality, showed a hunter the way to their roost.” As to his insatiable appe- tite and greed, “ Even in the three watches of the night he is faint for want of food.” “Only when he swallows a rag dipped in ghee [liquid butter] will the crow feel full.”—(Nell.) The Ceylon magpie robin (Copsychus saularis ceylonensis), the coconut bird or the dawn bird, is heard in the early morning and evening. It has a song clear and sweet, although less melodious dur- ing the day, when it seems to repeat “ miyachchi”, or “ dead”, and hence is regarded asa bird of ill omen. The call is said to announce evil tidings. It is believed by the Hindus to be the incarnation of Huniyan-yaka, bringing misfortune to the healthy and death to the sick, and the villagers pelt it with stones to drive it away from their dwellings. If this bird builds a nest in a cabin, it is thought to be a great misfortune.—(Nell.) The Sinhalese explain the sorrowful note of the Ceylon spotted or ash dove as follows: A woman placed some kebella berries in the sun to dry and told her son to watch them carefully while she was away gathering firewood. As they dried they stuck to the ground so that they could barely be seen, and on her return she accused the boy of eating the fruit, and in her rage she struck and unfortunately killed him. She then in remorse killed herself and was transformed into a spotted dove, and she now flies through the forest mourning her lost son with the well-known cry of “ pubbaru puta pu pu” or “Oh! my young son.” The black patch on the throat of the male Indian house sparrow is, according to the legend, due to fire in a house where a pair had a nest, The hen flew away, but the cock battled bravely through the flames to rescue his young in the nest beneath the eaves. He scorched his throat and the mark still remains to testify to his bravery and paternal love. The building of a nest and breeding by sparrows in a house is considered a good omen, and to encourage them in this, chat- ties (earthern bowls) are often hung on the walls. If a sparrow makes a nest and rears her young in the house, the next child born to the owner will be a boy. Sparrows’ eggs broken and accompanied by proper incantations make a charm to stop an objectionable tom- tom by causing the collapse of the instrument. The shell reduced to powder, placed on a betel leaf, and mixed with certain other ingre- dients makes a potent love philter. Ceylon is abundantly supplied with interesting flycatchers of all sizes and colors. The beautiful paradise flycatcher is called by the 254 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 Sinhalese gini-hora (fire-thief) and kapu- or redi-hora, the former name from the fact that in his rapid flight through the forest his long, streaming tail feathers give this bird the appearance (in the younger or red phase) of flying about with a firebrand; in the (male) white or maturer state, he has the appearance of carrying off a bunch of cotton, hence his local name of “cotton-thief.” The long tail feathers form a prominent character of this attractive bird. The fan-tailed flycatcher reminds me both in appearance and habits of flight of the lovely New Zealand bird. It is a small (well-mixed) black and white species that tosses and tumbles through the air in pursuit of its insect prey while it repeats its song or call note, which translated into English is said to be “ Why don’t you pick the peaches quick? ”’—or by the more practical observer, “ Whisky, gin, and bitters.” It is by the latter phrase that this attractive species is most commonly known in Ceylon. A beautiful little blue and brown flycatcher, peculiar to the island, was first described by the American ornithologist, Oberholser— Cyornis tickelliae nesaea Oberholser. There are several so-called and well-known Ceylon “robins”, among them the very pretty black robin and the still more attractive magpie robin, just mentioned. Another rarer variety, the pretty little Indian red-breasted flycatcher, goes by the vernacular title of the hill robin. I need not add that none of these birds is even re- motely related to either the English robin redbreast or to our own American robin. One of the most curious of the indigenous birds of Ceylon is the red-faced malkoha (Phoenicophaés pyrrocephalus (Pennant)) that may be described as a mixture of cuckoo and magpie. It is a shy and rare bird (length, 18 inches; tail, 11 inches), living mostly on berries and inhabiting only the highest tree tops of the deep jungle. This species early attracted the attention of visitors and was described by Forster in 1781. The Ceylon iora (peculiar to the country) is another beautiful bird, like a small oriole, with its attractive black and orange markings. It generally occurs in pairs, inhabiting gardens and the leafy jungle. The male has a clear, sweet whistle of two notes; the nest is an artistic little cup bound to the bough or fork of a tree by cobwebs. Its sys- tematic name is Aegithina tiphia zeylonica (Gmelin), a long cognomen for such a small and dainty bird. Ceylon possesses several woodpeckers, some of them peculiar to the island. The pygmy (length 4.8 inches) is found nowhere else. It is a charming, dark brown, whitish-spotted bird. There is an odd Sinhalese folk-tale about the woodpecker. Once upon a time there was a korowaka (rail) who sold areca nuts. One day he flew to his BIRDS OF CEYLON—Wwoop Doe uncle’s at Velikilla, obtained a supply of nuts, hired some geese to carry the heavy bags to the waterside and there embarked with them in the keralla’s (woodpecker’s) boat. The overloaded boat capsized and both boat and nuts were lost. When the two birds reached the shore, the waterfowl abused the woodpecker for shipping his prop- erty on such a shaky old boat. “ But what ”, replied the woodpecker, “is your loss to mine? There are plenty of areca nuts, but where shall I find another such boat?” And so the woodpecker wanders about the world, tapping the trunks of trees, vainly seeking pieces of wood large enough to build another boat. The waterfowl still walks by the waterside crying “ kapparakata puwak puwak ” (a vessel full of areca nuts, areca nuts). That the geese also suffered is proved by looking at their deformed necks, bent and crooked from carrying heavy bags of nuts. There are a number of beautiful wild pigeons in Ceylon, among them the pompadour green pigeon (Z’reron p. pompadoura) that, by the way, has no cooing call, but a distinct whistle. This beautiful bird is an indigenous species, abundant all over the country. An even more lovely species is the Ceylon green imperial pigeon (Afus- cadivores aenea pudilla) , whose call is a distinct double “ coo-cooque.” This bird is 16 inchs long and presents an unusual display of color. I have made reference in several previous papers to that wonder- ful nest builder, the Indian tailor bird (Orthotomus s. sutorius), a common resident of Ceylon. Since then I have received from the island a number of other examples of the fine sewing, stitching, and suturing these little birds are capable of. I must once more empha- size here that, unlike those of certain nest-making ants, the stitches used by the tailor bird in sewing together so effectively the edges of a leaf or leaves are continuous, just like the plain sewing of the human seamstress. The cornucopea-like nest, which she afterward lines with all sorts of fibers, grass, moss, and cotton, although of delicate structure, often withstands the winds and rains of several seasons. ELE: Ae tS vit tian RIDE HAN " £ Fe a y + ary dit 1 Us Bd me oo i: ee Smithsonian Report, 1934.—Wood PLATE 1 2. THE CEYLON GRAY HORNBILL. ‘HS 18d8Vvgd YVLINIDS NOTARD AHL ‘1 9761 MM ea ec ALV1d POOM—PE6l *yuoday uerluosyynwg “LAHSuVvqg NOIWARD TIVWS SHL °2Z “ODNOYC GSATVL-LaAMSVY NOTASD FHL “1 PGS 7b Cameo Tipp, ALV1d poo A\—"pE6| ‘Oday ueruosyyIWG “‘VHOMIVW GS9V4A-GsyY AHL “2 “MYAHOLVOATA ANTE S.YSASTOHYHAEO *1 Vv 3LV1d P°°A—'bE6l *qaodayy uetuosyzIWig “YAMODAdGOOM AWSDAd NOIARD AHL °2 WHO] NOWdASaS Ante SL G ALV1d pooA—"p¢6| ‘q4oday ueruosyytug THE INFLUENCE OF CIVILIZATION ON THE INSECT FAUNA IN CULTIVATED AREAS OF NORTH AMERICA’ By Rocer C. SMITH Kansas Agricultural Experiment Station, Manhattan, Kans. The most striking characteristic of present day civilization is change. Nothing remains stationary or unchanged in the march called progress. Man has taken literally the task of transforming the face of the earth. As a result of his efforts, plant and animal life have been as strikingly affected as the fields and plains. He has, in a large measure, disdained nature’s crops and planted crops of his own choosing. Since animals as a group largely depend on plants for food, as the flora changed the fauna followed suit. Man has upset the ancient balance in the cultivated areas, and agricul- ture and biological conditions have been kept in such a turmoil of change that no new balance has been yet set up.? By cultivated areas is meant the farms and gardens, the trans- formed hillsides, valleys, and plains. The transformation has been a replacement of a sod containing many species of plants to a more or less pure culture of one plant. There is also a marked tendency towards specialization of crops involving large acreages in the culti- vated areas of North America. Our attention turns quickly to defi- nite, more or less circumscribed regions, when the following crops are mentioned: Wheat, corn, cotton, citrus, sugar cane, sugar beets, apples, peaches, plums, blueberries, dates, and celery. This speciali- zation tends to upset the balance even more completely than if the crops were generally diversified. Plowing up the native sod, clearing the forests, and watering the desert affected markedly the insect fauna of the region. The cli- mate, meteorologists claim, has not been appreciably affected by these activities, but soil climate has been markedly affected. So the greatest factor has been the change in food plants for the hosts of insects. 1 Contribution no. 404 from the Department of Entomology. Reprinted by permission from Annals of the Entomological Society of America, vol. 26, no. 3, September 1933. 2Smith, Roger C. Upsetting the balance of nature, with especial reference to Kansas and the great plains. Science, vol. 75, pp. 649-654, 1932. 257 258 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 DECREASE IN CERTAIN SPECIES OF INSECTS Some insects are less plentiful now because of these agricultural activities and because of the incidents connected with the progress of civilization. The periodical cicada has been adversely affected by civilization. The great swarms rending the air with their shrill music and causing bushes to bend under their weight will before many generations exist only in story. Bumblebee nests are much less frequently encountered during ordinary farm operations than was the case 30 years ago. Civilization has been unfavorable to bumble- bees and to field mice whose nests are often used by the bumblebees for making their nests. Outbreaks of grasshoppers are becoming less frequent in Kansas because of improvements in control measures and of decreasing areas of suitable breeding places. Grasshopper outbreaks are not characteristic of areas of intense cultivation on small farms and gardens. Such insects as the spring canker worm, which 30 or 40 years ago defoliated orchard and shade trees almost unchecked, have been re- duced by spraying for the codling moth, a more serious and more recent pest. Likewise, dusting cotton for the cotton boll weevil has relegated the less serious pest, the leafworm, to a minor place in some of the cotton-growing areas. Thus artificial control measures for the more serious pests have reduced some secondary ones also. Invention even enters in here, for collectors of dung beetles say that some species of this group of Scarabs are not so easy to collect since the decrease in the use of horses in transportation. One won- ders, when he sees radiators of automobiles plastered with insects, especially butterflies, dragonflies, and grasshoppers, whether this de- vice of modern civilization might not become a more important factor in the reduction of populations, both insect and vertebrate.’ Sanitary and health measures have brought about a probable reduction in many forms of importance in the field of medical ento- mology. Extensive paving of roads and streets, river improve- ments, better drainage on farms and cities, together with the exten- sive propaganda about mosquito-borne diseases, have kept down mos- quitoes, particularly in cities, except for sudden increases following periods of heavy rains. The great reduction of horses in cities has reduced fly-breeding opportunities. The widespread understanding of food contamination has placed the typhoid fly on the public enemy list. Parasitic forms dependent on wild animals become less plentiful as their hosts decrease, unless they select new ones. The hippoboscid 3 Fernald, H. T. Automobile as an insect collector. Bull. Brooklyn Ent. Soc., vol. 26, no. 5, pp. 231-233, 1931. CIVILIZATION AND INSECTS—SMITH 259 (Lipoptena depressa) and the head maggot (Cephenemyia sp.) of deer may be cited as examples. SOME SPECIES OF INSECTS HAVE INCREASED IN NUMBERS It is easier to cite examples of forms which have increased as a consequence of the activities of civilization. In the days of the old prairie, many species of insects subsisted on the perennial grasses, but the food supply was not abundant enough to permit the great increase of any one species.* Under farming conditions there is no longer a great number of species generally intermixed, but a few species present, sometimes in very large numbers, in the almost pure stand of some crop. A very large group of insects has adopted as food plants these new crops which have partly replaced the primitive flora. When the potato was brought to North America and was carried to the home of the Colorado potato beetle, there was provided a real opportunity for expansion for these insects. The potato, being a member of the same plant genus as the beetle’s native food plant, the buffalo bur, was promptly accepted, and between 1824 and 1893 the beetle had attacked the introduced potato plant from the Gulf States to Canada. This potato beetle has accepted the eggplant and, less commonly, the tomato, peppers, and tobacco for food plants also, all of which belong to the nightshade family. The chinch bug, a native feeder on some wild grasses of the great plains, did not become plentiful until acres of corn, oats, wheat, and grain sorghums were provided by modern agriculture. The corn ear worm must have had a discouraging time, if one can judge by present field conditions, before corn, cotton, tomatoes, and the rest of its adopted food plants were made available by civilization. The Hessian fly bred on some ancestor of modern wheat, or on other wild grasses, including wild rye, before civilization provided acres of wheat for it to feed upon. In North America, it has never been abundant except on wheat, barley, and rye, but it is known to run its life cycle in small numbers interchangeably with certain wild grasses, particularly of the genera Agropyron and Elymus.’ While in its native Kuropean home the Hessian fly had only one or two generations a year, in the central part of the United States it could generally have three generations a year, and sometimes in southern Nebraska, most of Kansas, and northern Oklahoma, it could have four or five generations. This indicates how much more favorable the climate and food conditions are in its adopted country. 4Metcalf, C. L., and Flint, W. P. Fundamentals of insect life, pp. 412-416. New York, McGraw-Hill, 1932. 5 Noble, W. B. Two wild grasses as hosts of the Hessian fly. Journ. Agr. Res., vol. 42, no. 9, pp. 589-592, 1931. 111666—35——18 260 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 Most of the grass-feeding forms still retain their original food plants and habitat while reaching out to conquer new worlds. The orass-feeding cutworms and wireworms often occur on crops in out- break proportions, particularly on wheat, corn, and alfalfa. Small armyworms are said to overwinter in grass plots. The fall army- worm often appears in numbers in bentgrass lawns or plots before it does in wheat or alfalfa. The army cutworm, the greasy and well- marked cutworms, when scarce, can often be collected to best ad- vantage in grass lands, under stones, boards, or trash. Likewise, certain species of wireworms occur in similar locations, especially in the early spring. It is but a short step from the wild grasses to the cultivated ones, such as corn, wheat, sorghums, etc. White grubs are worst in grassy fields or gardens. It is but a short step from feeding on the roots of lawn and pasture grasses to strawberries, potatoes, corn, and many other crops. The wheat stem maggot (Aeromyza americana Fitch.) has shifted from wild grasses to wheat and has found the change advantageous. False wireworm larvae formerly fed on weed seeds and decaying veg- etable matter on or under the surface of the soil in the Great Plains region. It was a logical move to feeding on the kernels of fall-sown wheat in the drier portion of the Great Plains States when germina- tion was delayed. The mole crickets, normally satisfied with the roots of grasses, damage potatoes in the Gulf States, while the Puerto Rican mole crickets, lifting the soil around young celery plants in Florida, have become major enemies to the celery growers. The tile-horned Prionus (Prionus imbricornis Linn.), a native in- sect feeding among the roots of big bluestem grass, has lately been found to be a serious apple-tree pest in Arkansas. The harlequin cabbage bugs, striped cucumber beetles, melon aphids, and tarnished plant bugs all find food plants more diverse and favorable as a result of modern agriculture, and are probably more plentiful as a result of it. Termites probably were natural feeders on sod, shrub, and forest remains before civilization provided houses with the attractive oak and hard pine floors. In their former role, termites were nature’s aids in the return of humus to the soil. Now they are aids chiefly to carpenters and lumber dealers by making rebuilding and _ re- pairing necessary. The shift from wild food plants to cultivated ones is most marked among fruit insects.° From wild plum came the plum curculio and the peach-tree borer; from hawthorne the apple maggot, the lesser 6 Herrick, Glenn W. Manual of injurious insects, p. 18. Henry Holt, 1925. CIVILIZATION AND INSECTS—SMITH 261 apple worm, and quince curculio; from wild crab came the round- headed apple tree borer and the light apple redbug. These forms thrive among the acres of plum, cherry, prune, and apple orchards developed as a consequence of modern agriculture. Apparently the famous blueberry of the maritime provinces of Canada and New England has an increasing list of insect enemies. This plant, largely uncultivated, forms the basis of a million-dollar industry in Maine. A recent study of this plant added, over the lists of previous writers, 80 insect pests depending on the blueberry for food.” The apple curculio (Tachypterellus quadrigibbus Say), a native insect which fed on hawthorne and wild crabs, has lately become a severe pest of apples in northeast Kansas, and the greater the neglect or poorer the orchard sanitation, the worse the damage. Another species of this genus has lately been noted to be a cherry pest in Colorado.® The walnut husk maggots (Rhagoletis juglandis Cress.) were until recently innocuous dwellers under the hulls of the common black wal- nut and a few other similar hosts. While they still occur on their wild hosts, these insects in recent years have appeared in Arizona and California, where they have produced a problem for the English walnut growers. Asa result of their feeding in the hulls of English walnuts, the nuts are stained and rendered less marketable. The plum gouger was an unimportant feeder on wild plums, but has increased under modern orchard conditions. The grape berry moth, grape flea beetle, and the grape root worm, all of which fed on wild grapes, have found expansive opportunities very favorable in modern vineyards. The beet leafhopper, during the summer, forsakes its wild food plants in the foothills or desert for the beet fields. After spreading havoc in the beet fields, some of these insects return to their wild food plants in the foothills. A recent increase in curlytop damage to beets in Utah is said to be due to new breeding grounds of favorable host plants on thousands of acres of abandoned dry farms.? This situa- tion raises the question of what will happen when man begins to abandon agricultural lands if the soils are depleted or the price of the products makes their continued cultivation unprofitable. Such pests as the beet leafhopper and grasshoppers are likely to be favored by that step. ™Phipps, C. R. Blueberry and huckleberry insects. Maine Agr. Exp. Sta. Bull. 356, pp. 107-232, figs. 17-24, 1930. 8List, Geo. M. A cherry pest in Colorado. Colorado Agr. Exp. Sta. Bull. 385, 106 pp., 1932. ® Knowlton, Geo. F. The beet leafhopper in northern Utah, Utah Agr. Exp. Sta. Tech, Bull. 234, 64 pp., 1932. 262 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 INCREASE DUE TO IMPORTATION A glance at the extensive list of injurious insects in North America which have been introduced, impresses one with the importance of this heading.” Thirty-seven out of 73 of our most injurious pests have been imported from other countries. More recent introductions include the Japanese beetle, European corn borer, pink boll worm, oriental fruit moth, European elm scale, and the lesser corn stalk borer. All of these are in the stage of dispersion at the present time. Many others, kept out by determined vigilance, are intercepted every year by quarantine inspectors at ports of entry. THE INTRODUCTION OR DEVELOPMENT OF NEW CROPS The introduction of new crops to North America has resulted in the pests of the crop following close behind. The semitropical crop of cotton, fed upon by the Mexican cotton-boll weevil, is now attacked by this insect over nearly the whole of the cotton belt, even when grown well northward in the temperate region. Citrus pests fol- iowed the introduction and extensive development of citrus fruits in Florida, Texas, and California. Each of the three districts has a somewhat different coterie of pests with which to contend. The areas for growing Sudan grass have been limited largely by the chinch bug. Sweet corn is attacked too severely in the sub- tropical regions by the corn-ear worm, the armyworm, and other pests to be a commercial possibility. There has been a marked increase in the number and destructive- ness of pests of pecans attacking the trees or nuts of this relatively new crop. Many of the pests have transferred from other trees, es- pecially hickory, black walnut, oak, and similar nut-bearing trees. Some of the worst enemies have not spread as yet throughout all the pecan-growing regions. The changing status of the insect pests of farm legumes and the shift to the new hosts as they increased in acreage is a situation sufficiently recent for present-day entomologists to have observed. Crimson clover was the first legume to be used extensively as a hay and soil-building crop. Then, about 60 years ago, alfalfa was intro- duced. This crop was relatively free of insect damage until about 20 years ago when the clover insects had so thoroughly adopted it that insect damage became a grower’s problem. Then came winter vetch and sweet clover, which the alfalfa insects rather promptly adopted. Cow peas and soy beans are also attacked by some of the old clover insects. Lespedeza shows no insect damage in Kansas so far, but the clover or alfalfa insects will no doubt in time adopt it as a food 10 Herrick, Glenn W. Manual of injurious insects, pp. 16-17. Henry Holt, 1925, CIVILIZATION AND INSECTS—SMITH 263 plant. A similar trend is shown in the shift of grass insects to corn and to the many kinds of feterita and sorghums. The papaya, avo- cado, date palm, and similar lately commercialized fruits in the United States, not yet severely attacked, may be expected to serve as hosts to some serious insect pests before many years. The introduction of new crops into North America is likely to continue indefinitely. These new crops probably will be free of severe insect damage at first, but soon pests, by transfer or importa- tion, will harass them. This has been the course of events in the past. It will be interesting to observe the building up of the list of pests of such new crops as the tung-oil tree in Florida, and the pine- apple in the West Indies, lespedeza and the Chinese elm in the Great Plains. INFLUENCE OF MODERN TRANSPORTATION In the last century, civilization has become increasingly in a hurry to go places. Consequently, means of transportation have become more varied and speedy. The excellent transportation facilities provided since the first railroad in 1829 have been a great aid to insects in extending their domain. Gypsy and brown-tail moth larvae have been noted to drop on automobiles and be whisked off to new feeding grounds. Egg masses of the gypsy moth were shipped to Cleveland from New Engiand on stone intended for building con- struction. Quarantine officers during the summer stop automobiles in certain sections in search of European corn borer stowaways on green corn. The possibility of importing, in airplanes, infected yellow fever or malarial mosquitoes from Central American coun- tries to the shores of the United States has received consideration. Likewise, the danger of spreading the West Indian, Mexican, and the Mediterranean fruit flies in fruits carried by passengers who may discard them, innocent of possible consequences, has been pointed out repeatedly. So by railroad, steamboat, automobile, airplane, zep- pelin, and all other transportation devices, insects spread their rav- ages much faster than by the legs and wings provided by Mother Nature. PHYSIOLOGICAL STRAINS OR VARIETIES Plant breeding and exploration have resulted in great assemblages of not only many kinds of plants, but also of many strains of these plants. One needs only to think of the many kinds of apples, peaches, plums, and cherries; of the many kinds of wheat, corn, grain sorghums, and of most every other variety of crop grown. It has been found that there are different strains of the insects, which strains are geographically distributed according to the crop. 264 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 The blueberry maggot is an example of incipient species forma- tion. A strain attacking apples has developed and reached the degree of separation so that each form can perhaps exist independ- ently upon its respective host. It is reasonable to believe that man, by creating genetically different strains of plants, must, in time, deal with the attacks of increased numbers of physiological strains of some of their insect feeders. This appears to be explained by adapted strains of the insects being able to survive while unadapted ones perish.” Codling moths sent from Colorado to Virginia did not behave with respect to their ability to enter sprayed apples as did the codling moths of Virginia."® It was concluded that in this regard there were different strains of codling moths in the two States. Some strains of wheat lightly attacked by the Hessian fly in Kansas have been se- verely attacked in Illinois.1* It is the soft wheats which furnish many resistant strains in Kansas, while, according to the literature, in Russia the hard wheats furnish more of these strains. The semi- hard variety, Kawvale, is more heavily attacked by Hessian fly in Indiana than in Kansas. BENEFICIAL INSECTS Some insects accomplish useful services to mankind and are, there- fore, introduced, propagated, and encouraged by man. Here follows a host of parasite introductions of the European corn borer, Japa- nese beetle, gypsy moth, ete. More than 50 parasites, including both native and introduced, now attack the oriental fruit moth and they offer man the chief hope of control. The introductions to control citrus pests have achieved notable results. Trichogramma adults have been propagated and released for the control of the codling moth, sugarcane moth borer, European corn borer, oriental fruit moth, and the greenhouse leaf tier. The introduction of the fig insect in 1901'* made possible the fig industry of California. While the caprification of figs is an essential part of that industry, it has been discovered to be complicated by the dissemination of the stem rot of these fruits. It has, however, been found possible to produce these insects in the laboratory, uncontaminated by the spores of this disease. 11Qathrop, F. H., and C. B. Nickels. The biology and control of the blueberry maggot. * *, * [Uc SS. Dep, Agr, Techs Bulls 275, 16upp.,) 1932. 12 Thorpe, W. H. Biological races in insects and allied groups. Biol. Rev., vol. 5, pp. 177-212, 1930. 13 Hough, Walter S. Studies of the relative resistance to arsenical poisoning of dif- ferent strains of codling moth larvae. Journ. Agr. Res., vol. 38, pp. 245-256, 1929. 14 Painter, R. H., et al. Resistance of varieties of winter wheat to Hessian fly. Kansas Agr. Exp. Sta. Tech. Bull. 27, 58 pp., 1931. 18 Condit, I. J. Caprifigs and caprification. California Agr. Exp. Sta. Bull. 319, pp. 341-375, 1920. CIVILIZATION AND INSECTS—SMITH 265 The honeybee is not a native North American insect, but was introduced by the early, thrifty colonists to function as one of the earliest factories on the continent. It is estimated that there were 4,620,650 colonies of bees in the United States in 1931 and that these colonies produced about 160,000,000 pounds of honey.t® This is an industry of no mean proportions. The honeybee has remained un- changed by centuries of domesticity, but its effect on civilization is measurable. In addition to the production of honey and wax, these creatures are receiving increased recognition as pollenizers of or- chards. The late increase in the acreage of sweetclover has pro- vided them with an additional excellent source of nectar. LIMITATIONS PROVIDED BY CIVILIZATION Insects do not have complete freedom in their spread. Man has set up various mechanical and artificial barriers which are more or less effective to their invasions. One thinks at once of the many quarantines enacted and promulgated to keep out undesirable foreign pests and to prevent or check the spread of those already introduced. Examples are too familiar to repeat. The range and abundance of the Texas fever tick is being reduced markedly in the southern States. Large areas are now tick-free, owing to the persistent prosecution of a systematic program of tick eradication. Man is the insect’s worst enemy. He destroys them by barrages of poison gas, with poisoned food, and with merciless mechanical de- vices which trap them, crush them, or keep them out of the most attractive places. He burns them, scalds them, freezes them, starves them, or drowns them. Furthermore, he gives aid and comfort to their other enemies, such as their parasites, predators, and diseases. But where in the animal kingdom is such tenacity and persistence displayed as in insects? It is truly the battle of the centuries. Finally, the competition offered by insects to civilized man has forced him to be a better farmer and citizen. This point should be mentioned in a low tone of voice because inborn prejudices regarding the joy of work make this a difficult point to evaluate. Nevertheless, plowing under the wheat stubble promptly after harvest to destroy the Hessian fly puparia has resulted in better seed-bed preparation for the next crop, while the fly-free planting dates in many commu- nities are very near to or coincide exactly with the planting date for maximum yields. The mosaic disease carried by the corn leaf or sugarcane aphid (Aphis maidis) so seriously damages native vari- eties of sugarcane in the West Indies that mosaic resistant varieties %#* Olsen, Nils A. Estimated colonies and yield of honey by states, 1928, 1929, 1930, and 1931. U.S. Dep. Agr. Bur. Agr. Econ. Mimeogr. leaflet, Nov. 15, 1932. 266 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 of P. O. J. cane have been introduced, resulting in great increases 1n yields. Plowing under crop residues is an effective check for many insects, such as garden insects, European corn borer, wheat stem maggot, Hessian fly, celery leaf tier, and many others. This practice restores humus to the soil and provides for better aeration. It is good agro- nomic practice. Crop rotations tend to build up the soil or at least prevent its too rapid depletion and generally thwart insect pests. A large part of the increased yields obtained from a rotation where grains follow legumes and legumes follow grains is due to the reduction in insect damage. Creosoting railroad ties and telephone poles to protect them against termites has protected them also from saprophytic fungi. CONCLUSION The progress of civilization can be interpreted in the changing status and range of many insects. This change is noted chiefly in those of economic importance but, by analogy, one may infer that many rare and unusual forms have been equally affected. However, because of their scarcity or lack of importance with reference to modern agriculture, this change is either unknown or less understood. Every specialist finds the study of species distribution very fascinat- ing. One can never be certain whether unusual distributions or long gaps between localities in which the species occur may not be due to transportation agencies of man. The tendency toward specialized agriculture is favorable to the unbalancing of species of insects re- lated directly or indirectly to the different hosts. ‘This has necessi- tated a fiercer warfare to produce a satisfactory crop. Insects may not have learned nor consciously changed to fit the ever-changing conditions of civilization, but through survival of successful strains have just as fully met each move successfully. A stabilized environ- ment for these creatures is as far away as the end of evolutionary development itself. ARCTIC BUTTERFLIES By AuSTIN H. CLARK Curator, Division of Echinoderms, United States National Museum [With 7 plates] THE FAR NORTH AS A HOME FOR BUTTERFLIES No temperatures that are found in nature are too low for butter- flies—that is, for certain kinds of butterflies. We look on butterflies as harbingers of spring and as nature’s dainty ornaments of our fields and gardens in the sultry days of summer. Yet some of them in their early stages can withstand the severest cold of an arctic winter, or the still severer cold at Verkhoyansk in northeastern Siberia, where the mean temperature in January is 60° below zero, and on some days it gets much colder. Covered with ice and snow and all but inaccessible is the grim Arctic waste of Grinnell Land, just across the narrow Kennedy Channel from northwestern Greenland. Here at Lady Franklin Bay the average winter temperature is 36° below with a minimum of 73° in March, and the average summer temperature is only 34° above. Almost identical temperatures are found at Floeberg Beach, on the northern coast of Grant Land (lat. 82°27’ N.), facing the Polar Sea with its paleocrystic ice—permanent ice of unknown age. Desolate and forbidding as this ice-bound region is, it is far from being as barren as it looks, for plants are to be found wherever there is soil enough and sufficient warmth from the rays of the Arctic summer sun to nourish them and to permit their growth. Indeed, in this region of perpetual ice and snow where the winter temperatures are mostly below the freezing point of mercury there is a surprising wealth of plants, many of them with conspicuous and very pretty flowers. No less then 75 different kinds of vascular plants have been collected there. This sounds almost incredible. Still more incredible seems the fact that from this grim region of eternal ice the British ships Dés- covery and Alert brought home no less than 35 gaily colored butter- flies belonging to five different species, and two kinds of brightly colored bumblebees. 267 268 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 Col. Henry Wemyss Feilden, who was attached to the Alert as naturalist, said that during the short period when there is practically no night, butterflies are continually on the wing, if the sun’s face is not obscured by clouds or passing snow showers. He also said that about 1 month in every year is the longest period in which it is possible for these insects to appear as winged adults, and that about 6 weeks is the limit of time allowed plant-feeding caterpillars, the land during all the rest of the year being under snow and ice. The caterpillars living in this region may be frozen until they become as hard as ice and as brittle as rotten twigs; yet when it warms up and they thaw out they come again to life, and begin to feed in the most unconcerned manner. In northwestern Greenland, according to Prof. Emil Vanhoffen, beetles, butterflies, moths, wasps, flies, and a few other kinds of in- sects inhabit the whole rocky coastal strip that borders the inland ice, and some kinds have even been found on the nunataks—rocky islands entirely surrounded by ice. Wedged in between two ice streams of great size, with a third of its coast line on the sea, the Karajak nunatak has a rich insect fauna. On this large island be- tween the sea and the inland ice the insects are better protected than they are on the smaller nunataks that are entirely surrounded by the ice. Here both plant feeding and predaceous insects are in evidence, though only a few kinds are abundant. The butterflies and moths are more numerous both in individuals and in kinds than the wasps parasitic on them—their caterpillars know very well how to conceal themselves. Far to the east of Greenland, curving in an irregular crescent about the western border of the Kara Sea south of Franz Josef Land, hes Novaya Zemlya, a long, narrow island divided near the middle by a& narrow winding channel called the Matotchkin Shar. It is sep- arated from the Siberian mainland only by the Kara Strait and Vaygach Island. The climate of Novaya Zemlya is colder than that of Spitzbergen, though it is milder than that of the northeastern portion of Siberia. In the middle portion of the western coast the average temperature in the winter months is —4°. The average summer temperature at the Matotchkin Shar is 36.5°—lower than it is at Boothia Felix or on Melville Island north of North America—and toward the south the temperature decreases. On the eastern coast the summer tem- perature is lower than it is on the western coast. But thanks to the influence of a current that bathes especially the northwest coast— which may be considered as the extreme northeastern limit of the Gulf Stream drift—the shores of Novaya Zemlya are less ice-bound ARCTIC BUTTERFLIES—CLARK 269 than perhaps might be expected. Indeed, there are years in which the island may be circumnavigated without difficulty. On Novaya Zemlya plant life is restricted to usually small patches, and it possesses but a scanty flora. In all there are about 160 differ- ent kinds of flowering plants, which show affinities rather with Arctic Asia than with Arctic Europe. The desolate land shows hardly a trace of animal life. Even insects are few both in kinds and numbers. But inhospitable as this island is to land-living creatures, it is the home of three different kinds of butterflies. In rigorous regions such as these, butterflies are found, ranging northward to scarcely more than 500 miles from the Pole itself. Much farther south than this are regions seemingly more attractive and hospitable where no butterflies exist. UNCONGENIAL REGIONS FARTHER SOUTH Four hundred miles north-northwest of the North Cape, Europe’s most northern point, somewhat farther south than Grinnell Land, hes the archipelago of Spitzbergen. A group of rocky, barren, and ice-bound islands lost in the Arctic Ocean—such is the Spitzbergen archipelago. High mountains and ice-covered plateaus make up the greater portion of its surface. Thanks to the influence of the north- easterly drift from the Gulf Stream, its climate is less severe than that in the corresponding latitudes of Greenland and the islands farther west. At Mussel Bay the average temperature for January is 14.1° and for July 39.3°. Even in the coldest winter months a thaw may set in for a few days; but on the other hand snow sometimes falls in July and August. Spring comes in June, and by the end of that month the temperature has ceased to fall below the freezing point at night. Spitzbergen supports nearly 100 different kinds of plants, of which more than 80 are found also in Greenland, and about 70 live also in Scandinavia. Forty-three of them are very widely spread in Alpine regions, and have been found even as far away as the Hima- layas. The vegetation of the northern portion recalls that of Mel- ville Island, west of Baffin Land, while that of the south has much in common with that of Lapland and the European Alpine regions. With a milder temperature than that of Grinnell Land, and more different kinds of plants, one might expect Spitzbergen to be a more favorable habitat for butterflies. But no butterflies live there. The only representatives of the Lepidoptera are three different kinds of moths. East of Spitzbergen and slightly farther to the northward lies the ice-bound archipelago of Franz Josef Land. Here there are 270 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 neither butterflies nor moths. Half way between Spitzbergen and the North Cape lies Bear Island. Bear Island is almost entirely ice-bound, and is colder than Spitzbergen. Here also there are neither butterflies nor moths. Far to the southward of Novaya Zemlya’s latitude—indeed south of the Arctic Circle which it only just reaches in its northern por- tion—is the large and interesting island known as Iceland. The cli- mate of Iceland is not nearly so severe as might be expected from its latitude. In the south it is very wet, the rainfall is considerable, and snow storms and gales are frequent in the winter. The winter temperature is about 29°, and the summer temperature is about 53°. But the temperature varies much from year to year, the average temperature of the same month having been known to differ by as much as 27° in different years. In the north of Iceland (at Akureyi) the climate is dry and reg- ular. The summer temperature is about 45°, and the winter about 205. There are many different kinds of plants in Iceland but no trees, except for a few dwarf birches and some willow and juniper bushes. In Iceland there are about 35 different kinds of moths, but there are no native butterflies. Four kinds of butterflies have been cap- tured there, but all of them are stragglers from beyond the sea. These four visitors are the common cabbage butterfly (Pieris rapae), the red admiral (Vanessa atalanta), the painted lady (V. cardui), and the American painted lady (V. virginiensis). The painted lady is the most frequent visitor, and in some years rather numerous individuals cross the sea and reach the island. For in- stance, in July 1894 no less than five were captured. Nine other kinds of butterflies have been said to have been found in Iceland, but the records are erroneous. Iceland is too stormy and too wet for butterflies. Much farther south than Iceland, between the parallels of 51° and 55° north latitude in the North Pacific, lie the Aleutian Islands, of which the southernmost is in approximately the same latitude as Lon- don. Here the climate is very mild. In the winter the average tem- perature is scarcely less than 20°, though on occasion it may go as low as 7°. Throughout the winter months the temperature on certain days may rise above the freezing point. The soil does not freeze deeper than a foot or so at most, and in some winters it does not freeze at all. The sea about these islands is open throughout the winter. The seasons here are only two, a prolonged early spring and a short mild winter. But the sun is almost never seen. Gales and storms of ARCTIC BUTTERFLIES—CLARK 271 varying intensity, with fogs and mists and drizzling rains or flurries of snow occur almost continuously. A damp, raw, and chilly day with a light breeze in early spring is a fair sample of the pleasantest Aleu- tian summer weather. Here there are no trees, and only a few small bushes in protected situations. But wherever soil occurs there is luxu- riant vegetation, and many lovely flowers, especially lupines and anemones. In spite of the lovely flowers and the numerous and inter- esting birds I still remember the Aleutian Islands as the most forlorn region I have ever visited. No butterflies live in this depressing chain of islands. The climate, though not cold, is too stormy and too wet for them. The Pribilof Islands, north of the Aleutians, also have no butterflies, and only seven kinds of moths. The Aleutians and the Pribilofs have their counterparts in the Southern Hemisphere. To the eastward and somewhat north of Tierra del Fuego hes the archipelago of about 200 islands known as the Falkland Islands. Here the temperature is very equable, the aver- age for the two midsummer months being about 47° and that for the two midwinter months about 37°. The sky is almost continuously overcast, and rain falls, mostly as a drizzle and in frequent showers, on about 250 days during the year. The rainfall is not great, being only about 20 inches, but the mean humidity for the year is 80. Owing to the absence of sunshine and of summer heat, wheat will not ripen, barley and oats can scarcely be said to do so, the common vegetables will not produce seed, and no trees will grow. The sole butterfly of the Falkland Islands is a litle fritillary (Brenthis cytheris falk- landica (pl. 3, figs. 21, 22)) that has recently been described. Far to the eastward of the Falkland Islands and slightly farther north there lies, southeast of Africa, the large island called Kerguelen. Here the lowest temperature in winter is seldom less than 32°, and the summer temperature occasionally approaches 70°. But Kerguelen hes within the belt of rain at all seasons of the year and is reached by no drying winds. It has no trees, but on the lower mountain slopes there is much rank vegetation that is saturated with moisture con- stantly. There are no butterflies. The Lepidoptera are represented by a single kind of short-winged flightless moth, of which the cater- pillars feed on the curious plant called the Kerguelen cabbage. Both butterflies and moths are absent from all the other islands in the Antarctic seas and from the Antarctic continent. From this we see that the severest cold of the far northern regions can be withstood by certain kinds of butterflies. They will thrive in the most rigorous of climates, if only there is sufficient sunlight and sufficient food. But in wet and stormy regions, though the tempera- ture may be relatively mild and equable, they are unable to exist. 272 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 THE BUTTERFLIES OF THE FARTHEST NORTH Such is the background of butterfly life in the far north, where for only a few weeks out of every year activity is possible, where for at least 10 months out of every year all insect life is in abeyance— frozen into unconsciousness and inactivity. Yet under these conditions butterflies and moths are far from being rare. Only very slightly more than 500 miles from the Pole itself (lat. 82°45’ N.) there was found the northernmost representative of the Lepidoptera. This is a fair-sized moth (Dasychira rossz) of plain and dingy coloring. The caterpillar of this moth has been observed feeding on saxifrage on rocks projecting from eternal ice. Less than 40 miles farther to the southward, at Discovery Bay in Grinnell Land (lat. 81°52’ N.), Colonel Feilden captured two differ- ent kinds of butterflies. Both of these are little fritillaries (Brenthis polaris (pl. 2, figs. 18, 14) and B. chariclea (pl. 1, figs. 7, 8)), related to our common bog or meadow fritillaries, but dingier in color. The second of these (B. chariclea (pl. 1, figs. 7, 8)) Professor Vanhoffen found in northwestern Greenland flying commonly on moist sunny hillocks or over mossy meadows, though there were no flowers here for it to visit. These two little fritillaries range farther north than any other butterflies—at least they are known from farther north than any others. But only 9 miles south of the northern limit of their range in Grinnell Land (in lat. 81°45’ N.) three additional kinds of butter- flies were found by Colonel Feilden. One of these is a very pretty butterfly nearly or quite 2 inches in expanse with the wings orange on the upper side, in bright sunlight with a lovely violet iridescence in the males (pl. 4, fig. 33), narrowly black-bordered. This attractive insect (Colias hecla (pl. 4, figs. 33, 34)) is related to our common clover butterflies, which, with their yellow or orange wings, are so conspicuous in our open fields in summer. As in the case of its more southern relatives, the female is sometimes white. D. Jenness, who collected this butterfly on Barter Island off the northern coast of Alaska, said that it flies with con- siderable speed in a comparatively straight line for some distance. With one exception, his specimens were all taken when the sun was shining and the temperature varied from 44° to 56°. The one excep- tion was a male caught on a cloudy day when the temperature was 38°. With this pretty orange butterfly there flies a variety of our com- mon little copper (Chrysophanus phlaeas feildeni (pl. 6, figs. 49, 50) ) in which the fore wings are lighter in color and more fiery than in the form we know so well—bronzy rather than coppery—and the ARCTIC BUTTERFLIES—CLARK pas spots are smaller. The hind wings on the under side are a rather dark blue-gray. The third butterfly found in this far northern spot was a delicate and pretty little blue (Plebetus orbitulus (pl. 6, figs. 47, 48) ) seem- ingly so very frail as almost to make one wonder how it can exist at all, to say nothing of being able to live in such a place as this. All five of these butterflies are found in Greenland, where there is still another, a green relative of our clover butterflies (Colias nastes (pl. 4, fig. 86) ) somewhat smaller than the orange one. This a most disconcerting butterfly, for it is highly variable, and individuals taken in the same locality at the same time may differ widely in appearance. It is one of the three butterflies that live on Novaya Zemlya. The other two are both bog fritillaries (Brenthis). One of these two (B. chariclea (pl. 1, figs. 7, 8)) has already been introduced to us as an inhabitant of Grinnell Land and Greenland. The other (2B. improba (pl. 2, figs. 15, 16)) has not been found in either of these regions, though it lives north of North America in Baffin Land, up to about 70° north latitude, and in the extreme north of North America and Asia. In Baffin Land and the Arctic Archipelago north of North America, and along the northern coast of North America itself, where the climate is scarcely less severe than it is in the regions farther north, there live no less than 22 different kinds of butterflies, the 7 already mentioned and 15 more. Three of these are relatives of our common clover butterflies (Colias). One of them (C. booth2) lives in Baffin Land and on South- ampton Island in the northern part of Hudson Bay, and westward to Boothia Felix and Coronation Gulf. Another (C@. pelidne (pl. 4, fig. 85) ) is found in southern Baffin Land and Labrador, and west- ward at least to the Mackenzie River. The third (Colias mead?) is a very pretty butterfly, bright orange with broad black borders to the wings, that lives in the region of Coronation Gulf and also on the high peaks of Colorado between 9,000 and 12,000 feet above the sea. From Labrador to Alaska, and from northern Siberia to Lapland and to Finmark there lives a relative of these (C. palaeno (pl. 4, fig. 37)) that does not range quite so far into the high Arctic regions. It is interesting to note that in the yellow clover butterflies of the far north the females are almost always white and only very rarely of the normal coloration, just the reverse of what we find in their relatives in more southern latitudes. Of the bog fritillaries, so very characteristic of far northern regions, no less than four different kinds, in addition to the three already noticed, live in the extreme north of North America. One of these 274 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 (Brenthis freija (pl. 1, figs. 3,4) ) occurs from Baffin Land and Boothia Felix southward to Labrador and westward to Alaska, and also in the Rocky Mountains south to the high peaks of Colorado. In the Old World it lives from Finmark to eastern Siberia, across the extreme north of Europe and of Asia. Closely related to this species, and perhaps only a variety of it, is another (B. natazhati) that is found in the vicinity of Coronation Gulf and westward to the Alaskan border. In the region of Coronation Gulf and westward to Alaska still another kind (B. pales (pl. 2, figs. 17-20)) is found that lives also in northern Europe and eastward throughout Siberia. The last of the bog fritillaries found in the extreme north of North America (B. gibsoni) is known only from Southampton Island in the north- ern part of Hudson Bay. This is probably only a variety of a widely ranging species (B. frigga (pl. 1, figs. 1,2)) that lives from northern Norway and Finmark, Esthonia and Lapland, eastward to eastern Siberia, and in North America from Baffin Land southward to Labrador, westward to Arctic Alaska, and thence southward in alpine regions to the high mountain peaks of Colorado. Very different from the butterflies we have so far considered are the H’rebias (cf. pl. 3, figs. 29, 30), a group of which the Scotch argus and the mountain ringlet of Scotland and the north of England are perhaps the most familiar species. These are dark brown butterflies of small or medium size related to our wood nymphs. Three differ- ent kinds are found in Boothia Felix or in the southern portion of the Arctic Archipelago north of North America. Of these 3 kinds, 2 are found also in Arctic Asia. Related to these Hrebias are some other butterflies of small or me- dium size known by the general or generic name of Oenets (pl. 5, figs. 89-44). Like the Hrebias, these live when in the caterpillar stage on grasses. They are found in the southern portion of the Arctic Archipelago north of North America, and in the extreme north of Europe and of Asia. Four different kinds of these are known from the region of Coronation Gulf. The last of the but- terflies known to occur in the region of Coronation Gulf is the western checkered white (Pieris occidentalis). The western portion of northern North America is much more fa- vorable for plant and animal life than are the eastern or the central portions. Here the northern limit of tree growth reaches to the mouth of the Mackenzie River, whereas farther to the eastward it just reaches the southern shores of Hudson Bay and the southern end of Ungava Bay, thence running to the southern end of the Lab- rador Peninsula. Together with the trees, several of the butterflies of the north temperate region extend their range far northward in the general ARCTIC BUTTERFLIES—CLARK 275 region of the Mackenzie River. The familiar gray comma of the northeastern States (Polygonia progne) here reaches the Arctic Ocean, together with a relative of our eastern orange tip (Huchloé creusa (pl. 6, figs. 53, 54)). Along the Mackenzie River and in the adjoining portion of Alaska a number of different kinds of butter- flies pass the Arctic Circle that do not reach it farther to the east. The largest and most conspicuous of these are two handsome yellow swallowtails, our common yellow swallowtail (Papilio glaucus) and the swallowtail of Europe, which lives in northern North America as well as in Europe, north Africa, and northern Asia (P. machaon). Similarly, in western Siberia and in Scandinavia many butterflies of the temperate regions range north of the Arctic Circle. Among these are the European swallowtail (P. machaon), the cabbage but- terfly (Pieris rapae), the painted lady (Vanessa cardut), the small tortoise-shell (A glats urticae), a hair-streak (Callophrys rub), and a skipper (Pyrgus centaureae (pl. 6, figs. 51, 52)). From the Arctic portion of the Yenesei region in western Siberia 22 different kinds of butterflies are known, including 9 bog-fritilla- ries, 4 Hrebias, 2 Oeneis, a swallowtail, a skipper, a blue, a clover butterfly, a white, and the painted lady. Just south of this in the sub-Arctic portion of the same region 32 species have been found. In Arctic Norway there are 46 different kinds of butterflies, of which no less than 26 occur under the parallel of 70° north latitude— that is, well north of the Arctic Circle. : In the Arctic regions taken as a whole there are 105 kinds of butterflies, some of which, however, are more or less casual visitors, or more properly belong to the sub-Arctic regions. The largest of the Arctic butterflies are the two swallowtails, both of which are found in northern North America, though only one of these (Papilio machaon) is found in Europe and in Asia. Most numerously repre- sented are the nymphalid or brushfooted butterflies, of which there are 36, all but 10 of which are fritillaries. There are 27 wood- nymphs or satyrids, including 14 H’rebas and 7 representatives of the genus Oeneis. Of the lycaenids there are 19, including 12 little blues, 6 coppers, and a single hair-streak. There are 15 pierids, including 5 whites, 5 clover butterflies or coliads, and 3 relatives of our orange-tip; and there are 6 skippers. Of the 79 kinds of strictly Arctic butterflies 21 are found in all far northern regions—in northern Europe, northern Asia, and north- ern North America. Of the remainder, 25 live only in Europe and in Asia; 17 live only in America; 6 are found in America and Asia, but not in Europe; 5 are found only in Arctic Europe; 3 live only in Arctic Asia; and 2 are found only in Europe and America. 111666—35—19 276 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 THE BUTTERFLIES OF THE EXTREME SOUTH In the Antarctic regions the conditions are quite different from the conditions that are found in the northern part of the Northern Hemisphere. Here lies the great continent of Antarctica, which is too cold to support plants and is thus wholly devoid of insect life. More or less remote from this are various Antarctic and sub-Antarctic islands, on none of which do butterflies exist. The only continent that extends far enough southward to enter a region in any way comparable to the northern regions of the Northern Hemisphere is South America. But the climate of south- ern South America is wholly different from that of the northern portions of Europe, America, or Asia. Southern South America is so narrow that its climate is more like the climate of an island than it is like the climate of a continent. Across the Magellan Strait from the southern extremity of con- tinental South America lies the archipelago called “Tierra del Fuego.” The eastern portion of this archipelago consists of the island called King Charles’ South Land, an island very much larger than all the rest of the archipelago together, being considerably more than 200 miles in length from north to south. It forms a southern extension of the Patagonian pampas, which it much re- sembles in its physical constitution, and in its fauna and flora. The low-lying, flat, or slightly rolling plains are covered with a rich growth of tall herbage. In the south a long peninsula projects west- ward to the Pacific. This becomes rough and mountainous, with two peaks rising to nearly 7,000 feet—a true alpine region with numerous snow-clad summits and glaciers reaching to the sea. The western and southern portions of the archipelago are essen- tially mountain regions, resembling the western extension of King Charles’ South Land. They are extremely rough and rugged, with a much moister climate than the larger eastern island, and are densely forested, the forests consisting chiefly of an evergreen beech, and the glossy-leaved evergreen winter-bark. Above the forests, which rise to between 1,000 and 1,200 feet, there is a zone of peaty soil with stunted alpine plants that reaches as far as the snow line— that is, as high as from 3,000 to 3,500 feet. In this rough and forbidding land the winters are mild, with an average temperature of 32° for July, and the summers are cool, with an average of 50° for January, the warmest month. The mean temperature for the year is 42°. But throughout the year fogs, mists, rains, snows, and high winds prevail, and there are frequent and sudden changes from fair to foul weather. Tierra del Fuego is the same distance south of the Equator that the Aleutian Islands are to the north of it, and the temperatures ARCTIC BUTTERFLIES —CLARK DET and climatic conditions in the two island groups are very much the same. But the Aleutians have practically no sunlight, trees will not live there, and no butterflies are found in their grassy lowlands or on their boggy and mossy mountain sides. But forbidding as it seems, the Magellanic region possesses not less than 11, and possibly 12 or 18 different kinds of butterflies, most of which are singularly similar to others in the Arctic regions. Finest of all the Magellanic butterflies is a beautiful orange clover butterfly (Colias imperialis) known from Port Famine. Another orange clover butterfly (C. lesbia (pl. 4, figs. 31, 832) ), with the upper surface orange enlivened by a lovely violet iridescence and with much narrower dark margins to the wings, is also known from Tierra del Fuego. This second one ranges far to the northward, as far as southern Brazil, and also lives in the high mountains of Peru at an altitude of 12,000 feet above the sea. Two little fritillaries, much resembling the bog fritillaries so characteristic of the Arctic regions, live in Tierra del Fuego. One of these (Brenthis lathonioides (=darwint)) is only known from King Charles’ South Land and Punta Arenas, but the other (<. cytheris (pl. 3, figs. 23-26)) is much more widely spread, and is found in various forms as far north as northern Chile up to alti- tudes of 6,000 feet; it is also represented by a local form in the Falkland Islands (pl. 3, figs. 21, 22). This last is remarkable for the great difference in the under side of the hind wings in the two sexes (compare figs, 24 and 26, pl. 3). A pretty and delicate Little blue recalls the blues of Arctic and sub-Arctic regions. The arctic and subarctic ringlets (Hrebéa (pl. 3, figs. 29, 30)) are represented in the Magellanic region by four different butterflies, One of these (Hrebia patagonica) is surprisingly hike some of the ringlets from the northern hemisphere, but the broad red-brown bands on the upper surface of the wings include no eye spots. This butterfly is not known elsewhere. Another (Cosmosatyrus lepton- eurodes), which ranges northward in the mountains of Chile, recalls the Callerebias of Asia. A similar but smaller one ranges north- ward in the mountains to Bolivia (C. chiliensis (pl. 3, figs. 27, 28) ) The last is much hke these others, and also extends northward into Chile. All of these butterflies, superficially at least, are so closely similar to more familiar Arctic forms that at a casual glance no one would think of them as South American. But there are four others in Tierra del Fuego (Zatochila theodice, T. argyrodice, T. microdice, and 7'. demodice (cf. pl. 5, figs 45, 46) ) belonging to a type confined wholly to South America. In appearance these are not so very different from our northern whites, in their markings resembling 278 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 more or less our common checkered white. One of these is known only from a single female from the southern coast of Tierra del Fuego, two range northward to Peru, and one is found as far away as Ecuador and Colombia. Only four of the butterflies of Tierra del Fuego are confined to the Magellanic region. All the others range far northward, some living high in the Andes far within the tropics, and one even pass- ing the Equator and entering for some distance the Northern Hemisphere. Most of the butterflies of the Magellanic region range northward for a varying distance in the Andes, rising to higher and higher altitudes in the mountains until within the tropics they are found as high Alpine species. But one of them (Colias lesbia) lives as a lowland species as far to the northward as Brazil. Where do the Arctic species live beyond the Arctic regions? MORE ABOUT ARCTIC BUTTERFLIES One of the two bog fritillaries known from farthest north (Bren- this chariclea) has an extensive range, and is found over a wide extent of Arctic and Alpine territory. It lives from Grinnell Land and northern Greenland southward to Labrador, westward to north- ern Alaska, including Wollaston and Victoria Lands, and south- ward along the lofty peaks of the Rocky Mountains to the Yellow- stone Park. In the Old World it is found from northern Norway and Finmark eastward to Novaya Zemlya—that is, if B. émproba is considered as a form of it. In the Old World it is local and not very common, but in America it is more generally distributed and more abundant. It is rather plentiful about the lofty summits of our western mountains. Most interesting in connection with this butterfly is the existence of a flourishing colony far south of the southern limit of its range in Labrador in the White Mountains of New Hampshire. Here it lives in the subalpine zone of Mount Washington and the nearby peaks, and on the summits of the surrounding mountains. This is the only place where I have seen it. Mr. Scudder wrote that it is most common about the steep heads of the great ravines that have eaten their way into the heart of Mount Washington, and in the alpine gardens. But here it is never very abundant. It flies with no great rapidity close to the ground among the scanty foliage growing in the rocky crevices of the steep mountain sides. It is fond of sunning itself on the ground with fully, or almost fully, expanded wings, and whether on the ground or on a flower it moves about with similarly expanded wings. But when entirely at rest the wings are closed. ARCTIC BUTTERFLIES—CLARK 279 The individuals living in the White Mountains differ somewhat from their relatives living farther north and form a well-defined local race (montinus (pl. 1, figs. 5, 6)). The other far northern fritillary (B. polaris) lives also in Green- land and southward to Labrador (pl. 2, figs. 18, 14), thence westward along the extreme northern portion of North America to Alaska. It is found’ in Victoria Land and in Wollaston Land, and undoubt- edly elsewhere in the great Arctic archipelago north of Canada. In the Old World it lives in the mountains of northern Norway and in Finnmark, and ranges eastward in the north of Asia to north- eastern Siberia. But it does not occur in Novaya Zemlya. The bog fritillaries are especially characteristic of Arctic and sub-Arctic regions, and of alpine districts, though they are not con- fined to them. There are about 30 different kinds in the northern portion of the Northern Hemisphere. Many of these are very vari- able, locally or individually or both, so that many names have been bestowed upon them. Collectively they range over a vast extent of territory. They are found southward to the mountains of North Carolina and of Arizona, the islands in the Mediterranean, Asia Minor, Turkestan, the Himalayas in northwestern India, Tibet, western China, Mongolia, Korea, and Kamchatka. But strange to say, they are absent from Japan. They inhabit all sorts of regions from sea level as far south as southern Maryland up to a height of more than 15,000 feet in the Himalayas. Far removed from all their relatives are five little fritillaries corresponding to them that live in southern South America. Very different in their habits are the various kinds of these little butterflies. Those of the far north and of high mountain tops prob- ably require 2 years in which to complete their growth. One of the European ones is said to fly only in alternate years, at least in certain places. Most of them have a single brood a year, flying in spring or summer. A few in Asia, North America, and Europe have two broods a year. In North America some have three broods a year in the southern portion of their range, flying in spring, in summer, and in autumn; farther north, these have two broods, and still farther, only one. Our commonest bog fritillary in the east and north is prettily spotted with bright silver on the under side (2. myrina). It is not & very conspicuous insect, and unless you are on the watch for it it is likely to escape your notice. Its flight is direct, and for such a little butterfly it is rather fast. It alternately flaps and glides, keep- ing from 2 to 6, usually about 4 inches, above the ground or grass tops. The larger individuals found in the southern portion of its 280 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 range fly at the rate of 5 or 6 miles an hour, but the smaller individ- uals living farther north fly at the rate of 4 or 5 miles an hour. This butterfly is very unsuspicious, and if feeding on a flower in- variably may be captured with the greatest ease. If frightened when in flight, as by the close passage of the net, it usually closes its wings over its back and drops into the grass where it conceals itself, often quite effectively. More rarely it makes off with increased speed in a zigzag flight, but without rising above the usual height. This last peculiarity probably is due to its fear of dragonflies which in great numbers infest the places where it lives. Their plane of flight is higher than that of the bog fritillaries, and although they quickly seize any unlucky butterfly that rises to their level, they will not pounce on anything below them. This butterfly is unusually adaptable to changes in conditions. In the vicinity of Boston it commonly first appears in the last week in May, and early in June it has become abundant. A second brood is on the wing in the last week in July, and a third makes its appear- ance in September. In the vicinity of Washington it is not found until about the first of July, and disappears before the end of the month. Here there is only a single brood instead of three broods as farther north. Why should a butterfly appear only in midsummer in the South, but fly from spring to autumn in the North? Together with this little butterfly there lives another (B. bellona) having almost the same range and commonly found with it, but easily distinguished from it by the absence of silver spots on the under side. This closely resembles the other in its habits, but is not quite so active, though its flight is similarly rapid. The one with silver spots (B. myrina) is characteristic especially of open grassy bogs surrounded by rough and more or less scrubby pasture land, or of grassy river bottoms, but the one without the silver spots (B. bellona) prefers more uniformly wet localities, particularly the boggy and grassy banks of small streams in hilly or mountainous country, or small wet hillside pastures. One of the bog fritillaries (B. astarte) is described as being always found singly on the highest mountain peaks, not below 8,600 feet, far above the timber line. This one is exceedingly shy and difficult to catch. Its flight, especially the flight of the males, is very swift. It rushes and races about over the desolate rocky slopes with the wings constantly in motion, alighting but rarely, and then only for a moment. It is frightened by the least disturbance, and even the most cautious approach of the collector seems sufficient to drive it into precipitate flight. IF. H. Dod says of this species that the males play around the extreme summits of the mountains at 8,000 feet or higher. They are very difficult to net, as their flight is exceptionally ARCTIC BUTTERFLIES—CLARK 281 swift. The females are met with, though very rarely, much lower down, almost or quite at timber line (about 7,000 feet). Another kind (B. alberta), according to Edwards, flies on the steep upper slopes of the mountains, the females generally higher up than the males. The males spend most of their time racing restlessly up and down the slopes, flying so close to the ground that they appear to glide over the surface. Dr. Arthur Gibson says that this is less of a peak lover than the preceding, much more local and less common, but not nearly so difficult to capture. In one (B. pales) the small individuals that live in high alpine regions rush along close to the ground with a direct and very fast flight, with the wings moving rapidly and continuously. They are fond of basking in the sun on warm stones with the wings spread widely. But the larger lowland individuals differ in their habits from the smaller alpine ones. In most of these little butterflies the females are less active than the males, though the flight of the two sexes is very much the same. In many the females are noticeably less adept on the wing than males, and in a few (as in B. amathusia) the males have a rather rapid flight, the females a considerably slower and more labored flight. Bogs, moorlands, damp meadows, wet woods, and mountain sides, form the usual home of these little fritillaries; but some fly about dry hillsides as well as in boggy places, one (B. epithore) lives in the waterless mountains of Utah and Arizona as well as among more congenial surroundings, and one (B. hegemone) flies in the Kuruk- tag—dry mountains—in the Gobi desert in East Turkestan, southeast of Kurla. THE ARCTIC SATYRIDS Companions of the bog fritillaries throughout a large portion of their range are those somber brownish butterflies of small or medium size known as F’rebias (pl. 3, figs. 29, 30). The Hrebias as a whole range from the Arctic coast of North America, including the southern portion of the Arctic archipelago, southward to Hudson Bay, and in the west to the high mountain peaks of New Mexico. In the Old World they live from Scotland, northern England, and northern Norway eastward to northeastern Siberia and southward to southern Europe, Armenia, Kurdistan, northern Persia, Afghanistan, Kashmir, Tibet, Sikkim, and the mountains of central Japan. Far removed from any of its relatives, a single species is found in Patagonia. There are about 75 kinds of these somber little butterflies, and many are very variable, so that about 200 forms have been described. 282 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 About 70 live in Asia and in Europe, and 10 in North America; but 6 of the 10 found in North America are simply American varieties of Asiatic species. The Scotch argus and the mountain ringlet of Scotland and the north of England are perhaps the most familiar species of this group. But there are many different kinds in central Europe, and every visitor to the European mountains at the proper time of year must notice them—aindeed they are common over most of Europe. One of the commonest kinds is found over nearly the whole of Europe, and eastward to Amurland in eastern Asia. It lives in woods, in meadows, and along grass-grown roads. Its flight is slow, irregular, and somewhat skipping. The males are very common, but the females are much less often seen. They fly, as a rule, only toward the end of the season. Several of the Hrebias are woodland butterflies, some being found in damp pine woods, others in swampy woods, in shady places or in clearings in the forests, or in the woods of the subalpine region. The woodland species are generally sluggish with a slow, weak, and hesi- tating flight, and usually frequent rests. A few live both in woods and in open moorland. But most of the H’rebzas live in treeless regions, a few on the Arctic or high northern tundras, but the great majority on mountains above the timber line, ascending to a height of more than 14,000 feet above the sea. They frequent the beautiful alpine meadows and more or less barren grassy slopes, where one cannot fail to notice them. In general their flight is sluggish, direct, fluttering, and rather weak, with frequent rests, and they keep down near the grass tops. Some, however, have a stronger and more or less skipping flight. They are fond of resting on stones or on the bare ground in sunny places with the wings half opened. Many of them are fond of flowers, and some are fond of perspiration. On the barren ground of the mountain tops between the tree line and the snow, especially on rocky slopes, live many different kinds. These are not so easy to catch as are those of the alpine meadows. They have a rather rapid, hurried, and direct flight, keeping near the ground, and frequently flying off into places where it is impossi- ble to follow them. In spite of their dark and seemingly conspic- uous color they are very adept at concealing themselves. They are fond of sunning themselves on rocks with the wings half opened; but when so engaged they are rather shy. In Switzerland I have found them occasionally lying benumbed upon the snow with their wings closed. All of these butterflies that I caught in Europe proved to be males, and this is the common experience of amateur collectors. The fe- ARCTIC BUTTERFLIES—CLARK 283 males are very sluggish, and when they fly their flight is low, weak, slow, and awkward. For the most part they remain more or less hidden in the grass and do not fly until after they have mated and some of their eggs have been laid. Their eggs are not attached to the food plant, which is usually grass, but are simply dropped in grassy places. The fact that the Hrebias are grass feeders serves to restrict their distribution as high Arctic butterflies in favor of others that are less particular. A few of these butterflies are said to appear only in alternate years, at least in certain districts, and others in alternate years are more and less abundant. ‘The reason for this is that these species require 2 years in which to reach maturity, and adverse conditions have re- duced the numbers of one of the generations. The species of the related genus Oeneis are about 32 in number. Some of them are found in the southern portion of the Arctic archi- pelago north of North America, and in the extreme north of Europe and of Asia. About one-half live only in North America, about six are found both in North America and in the Old World, and about a dozen occur only in Europe and in Asia—chiefly in Asia. Taken as a whole the species of the genus Oeneis (pl. 5, figs. 39-44) have an enormous range. From southern Baffin Land they live west- ward to Victoria Island north of Coronation Gulf and to the north- ern portion of Alaska, and also from northeastern Siberia to the North Cape. Southward they are found as far as Nova Scotia, Bangor, and Mount Katahdin, Maine, Mount Washington, New Hampshire, Lake Superior and northern Michigan, North Dakota, Montana, and northern California, and in the western mountains southward to Arizona. In the Old World they range southward to Kamchatka, Korea, Mongoha, Tibet, southern Russia, the Tyrol, and Switzerland. But over this vast area they are very irregularly distributed. Thus in the eastern United States one species (QO. jutta (pl. 5, figs. 39, 41) ) is found only in a few bogs near Bangor, Maine, and in another bog in northern Michigan; another (0. katahdin (pl. 5, figs. 40, 42)) is found only on Mount Katahdin; and a third (0. melissa semidea (pl. 5, figs. 43, 44)) lives only on Mount Washington in New Hampshire and in its immediate vicinity. The first (O. jutta) eccurs in isolated and widely separated localities in Nova Scotia, Quebec, Yukon, and Alaska, and similarly in the Old World from eastern Siberia to Norway and southern Sweden. The second (O. katahdin) is known only from Mount Katahdin. Forms closely related to the third (OQ. melissa semidea) are found in Labrador, in the region of Coronation Gulf, in Yukon, and in Colorado. As a 2984 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 result of their very local and spotty distribution, most of the differ- ent species of these little butterflies have many local forms. No less than 70 of these have been described, of which nearly 40 are from North America. A number of forms that we now recognize as species are probably nothing more than varieties of other species. But undoubtedly many more remain to be discovered, especially in Asia. Very varied in their habits are the different kinds of these curious butterflies. Of the kind found on Mount Washington (0. melissa semidea) S. H. Scudder wrote that one would suppose that insects whose home is almost always swept by fierce blasts would be pro- vided with powerful wings fitting them for strong and sustained flight. But the contrary is true. They can offer no resistance to the winds, and whenever they ascend more than their accustomed 2 or 3 feet above the ground, or pass the shelter of some projecting ledge of rocks, they are whirled headlong to immense distances until they can again hug the earth. He said that their flight is rather sluggish and heavy, and has less of the dancing movement than one is accus- tomed to see in the satyrids. They are easily captured, though they fly singly, never congregating, and have their devices to escape pursuit. One of these devices is that when alarmed, and indeed at most times, they fly up or down the slopes, rarely along them, render- ing pursuit particularly difficult. Another is that they will rise in the air to get caught by the wind, which often takes them out of sight in a moment. One that he once followed with his eye whirled a good half mile away a thousand feet in the air, with a white cloud for a background. But according to Mr. Scudder the neatest device of all is espe- cially exasperating. One will settle on the ground a little distance off by a crevice in the rock piles, and as you cautiously approach you will see it edge its way afoot in its spasmodic fashion to the brink of the crevice and settle itself. ‘Then if you come nearer it will start as if to fly away, but instead close its wings and fairly drop down the crevice, where you may see it, but not reach it, to repeat the process and get still farther down if again alarmed by the re- moval of the upper rocks. In this way he more than once followed one for a couple of feet downward in a pile of small jagged rocks in one of the rock rivulets. Mr. Scudder said that this butterfly rests on the ground, or on the leeward side of rocks, as he often found it when searching on a cloudy day when it had not been on the wing. As soon as one alights it tumbles upon one side with a sudden fall, but not quite to the surface, exposing the under side of the wings with their mar- bled markings next to the gray rock mottled with brown and yellow ARCTIC BUTTERFLIES—CLARK 285 lichens, so that an ordinary passer-by would look at them without observing their presence. The surface of the wings is generally ex- posed so as to receive the fullest rays of the sun, or else the creature falls so as to let the wind sweep over it, its base to windward. In either case the fore wings are not fully drawn back between the hind wings. But when at rest for the night, or if the wind be sweeping fiercely, the fore wings are drawn completely back between the hind wings. These butterflies are fond of flowers, and often alight on the blossoms of the moss campion, or on some plant of the heath family, particularly blueberries. They are also fond of the flowers of the mountain sandwort. The best collecting places for this species are the sedgy plateaus of the northeastern and southern sides of Mount Washington. They are found most abundantly from about one-quarter to three-quarters of a mile from the summit, at an elevation of about 5,600 to 6,200 feet above the sea. He never found them about the heads of any of the deep ravines where the White Mountain fritillary (Brenthzs char- iclea montinus (pl. 1, figs. 5, 6)) is most common. Bogs and morasses form the chosen home of that relative of the White Mountain butterfly that is found near Bangor, Maine (0. jutta (pl. 5, figs. 39, 41)). Wherever it occurs it is to be found only in such uninviting places. And within the bogs themselves it is often very local, living only in a small section of them, only where sphagnum is abundant. This butterfly has rather a quick flight and is hard to catch. It rarely rises above the tops of the laurels and other low bushes of the bogs, seldom alights, and is fond of circling around the clumps of juniper bushes that here and there occur. When it does alight, it usually chooses tree trunks for a resting place. In the mating season the females usually rest high up in the trees, and in their search for them the males fly around and up the trunks. This insect is shy and easily startled. When it walks it moves by little jerks, with each jerk advancing less than one quarter of its length. If the wind blows upon it when it is at rest, it tucks the fore wings down between the hind wings so as to reduce the wing area as much as possible. Much larger and more brightly colored than these two is another kind that is found about the nothern end of Lake Superior (0. macounii). According to Mr. Scudder the movements of this butter- fly are swift, and in spite of their satyrid character are not unlike those of the viceroy (Bastlarchia archippus), which when on the wing it much resembles. These three native species well illustrate the diversity among the species of Oeneis as a whole. They live in swampy meadows, on grassy mountain slopes, along the edges of woods, especially coniferous 286 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 woods, in larch woods, or on dry, rocky, and barren slopes. Some prefer to rest on the branches of trees, others on the trunks, still others on rocks or on the bare ground, and a few hide in the grass, avoiding both rocks and trees. Some are fond of flowers, though others are seldom or never found on them. Many are shy, with a rapid flight, and difficult to catch; though some, especially such as live in grassy places, fly weakly and only for short distances. The females are much less active than the males, and in some kinds fly but rarely, so that they are much less often caught. Some of them in portions of their range are found only in alternate years, but in different years in different places, and these, and others, may vary more or less widely in abundance in alternate years. THE PIERIDS, LYCAENIDS, AND SKIPPER Especially characteristic of high Arctic regions are several different kinds of butterflies related to our common yellow or orange clover and alfalfa butterflies (Colias) that are so very common in our fields in summer. The butterflies of this group are very numerous, comprising about 80 different species. Many of these are very variable, locally, season- ally, or individually, and the females often occur in an albinistic as well as in a normal color phase. As a result of this variation more than 300 forms are recognized. More than half the species live in central Asia. In North America there are 15 species with 31 forms, most of them living in the north- west and in the mountains of the west, usually at high altitudes. There are eight species in South America, which are for the most part found high in the Andes from Colombia to Chile, but one lives on the southern plains, and one of the very finest of the genus is con- fined to Tierra del Fuego. Two are found in Africa, one throughout the continent, and the other in the northeastern section. In India south of the Himalayas one lives in the Nilghiri Hills. These butterflies live in open country, and especially in rough and mountainous country. Nearly all of them are active and fast fliers, the males especially. The little copper butterfly found in the far north (Chrysophanus phlaeas feildent (pl. 6, figs. 49, 50)) occurs in Greenland and south- ward to Southampton Island and to Labrador, thence westward to Alaska. In a somewhat modified form it lives in Norway, in Sweden, and in Finland. The species (Chrysophanus phlaeas) of which this is simply a geographical variety lives all over North America, except in the extreme south. In the Old World it ranges from the Arctic regions southward to Madeira and the Canary Islands, the oases of the Sahara, Asia Minor, northern India, China, and Japan. In the ARCTIC BUTTERFLIES—CLARK 287 Himalayas it is found 12,000 feet or more above the sea; but it is much more of a lowland than a mountain butterfly. In the Old World, especially in the southern portion of its range in Asia, it is extremely variable, both geographically and seasonally. It is also very variable in southern Europe. But it is much less variable in America. The pretty little blue of the far north (Plebeius orbitulus (pl. 6, figs. 47, 48)) is found in Greenland and southward to Labrador, thence westward to Alaska. Varieties, or closely related forms, range southward to the mountains of California and Colorado. In the Old World it lives from northern Norway across Siberia to Kamchatka and southward in the higher mountains to Spain, Asia Minor, Kash- muir, and Tibet. This is the commonest butterfly of the high Alps, and is even plen- tiful at the snow line. According to Dr. A. Seitz it is found locally in countless numbers in the region of the higher alpine pastures. It swarms everywhere over detritus and grass, always keeping close to the ground, settling with half-opened wings on flowers of all kinds. Often clouds of them assemble at small puddles in the roads, and they are even fond of drinking on the melting snow. When a cold wind from the glacier strikes them, or the sun is hidden by a cloud, they become at once lethargic and often helplessly tumble on their sides, remaining in this position until the warm rays of the sun revive them. Their flight is fast, but they are not shy. I have collected a number of them in Switzerland. The little skipper (Pyrgus centaureae (pl. 6, figs. 51, 52)) that en- ters the Arctic regions lives in Scandinavia and Finland, and also in the Altai Mountains. In North America it is found in Labrador and Quebec, and from northern British Columbia southward to the mountains of Colorado. It also occurs from southern New York southward to the mountains of North Carolina, where it is on the wing only in April and in early May. ARCTIC AND ALPINE BUTTERFLIES In the far north the butterflies make no distinction between low- lands and higher country, occurring wherever they can find support. Farther to the southward most of them become upland and finally alpine types. But this is by no means true of all of them. For instance, the little copper (Chrysophanus phlaeas) is not an upland species in Africa or in Japan, nor is it a true upland butterfly in the southern portion of the United States. The grizzled skipper (Pyrgus centaureae (pl. 6, figs. 51, 52)) be- comes an alpine butterfly in our western mountains, and in Asia in the Altai Mountains; but it is a lowland butterfly from southern New 288 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 York southward to Virginia, and not a true upland butterfly even so far south as Carolina. In this interesting southern colony it flies chiefly in the latter half of April, at the latest in early May, when the temperature is about the same as it is in midsummer in its northern or alpine home. In its early stages it withstands the intense heat of the prolonged southern summer quite as well as the intense cold of the long Arctic or alpine winter. The clover butterflies (Colias) and the bog fritillaries (Brenthis) are for the most part mountain or northern butterflies; yet both groups include southern lowland species. A number of different kinds of butterflies are confined to high alpine regions that do not extend into the Arctic area. On the high mountain tops in central Asia at a height of from 15,000 to 18,300 feet above the sea and even higher, in regions destitute of all traces of plant life, live some curious little butterflies belonging to the genus Baltia. According to Dr. R. Fruhstorfer these curious little pierids play in the sun or run about with half-opened wings over the sandy soil, sometimes traversing long distances. If they are dis- turbed they quickly hide away among the inequalities of the ground. When they fly they always keep near the ground. Very similar, though really only distantly related, pierids (Andina (pl. 4, fig. 38)) are found among the barren and desolate masses of rock on the highest summits of the Andes, at an elevation of about 19,300 feet above the sea. Garlepp, who discovered them, said he could not understand why this butterfly should choose such wastes and deserts, or how it can exist where there is absolutely no vegetation, where it must sometimes be daily covered with snow and ice, and where only the condor makes its abode. At these great altitudes tem- pestuous winds constantly prevail, so that the insect can fly only in the brief lulls. Probably the most familiar and most generally known of all the alpine butterflies are the lovely white parnassians (Parnassius (pl. 7)) so common in the European and Asiatic mountains, and in the higher altitudes in our western States. These are the largest of the alpine butterflies, and in Europe, Asia, and western North America they form a characteristic and most attractive element in the alpine landscape, especially of the higher mountain meadows and more or less verdant slopes, or at least green patches. There are nearly 30 different kinds of these lovely butterflies, and most of them are highly variable, locally and individually. They are found in the mountainous regions of Europe, except the British Isles, southward to Spain, Italy and Greece, in Asia Minor, and eastward to Kamchatka and the mountains of Japan, southward to the Himalayas. In North America they range from Alaska south- ARCTIC BUTTERFLIES—CLARK 289 ward in the mountains to New Mexico. Here they are represented by four different species with about a dozen forms. The species found in North America scarcely differ from others found in Asia. In the parnassians the flight of the males in the hot sunshine is easy and graceful. They progress by flapping and irregularly sailing with many turns and twists, stopping from time to time to feed on flowers with the wings expanded. They fly rather near the ground and rather hurriedly, and if it suddenly turns cold or rainy they take refuge in the herbage where their large size and white color makes them conspicuous. The females are less active than the males, and have a more clumsy and more fluttering flight, though when it is cold the males fly in the same awkward and hesitating manner as the females. Some parnassians have a curious habit of drifting irregularly up a valley in the morning, and down again in the afternoon. In the high altitudes at which they live exertion becomes difficult. One cannot chase a butterfly without very soon becoming distressed. But this curious habit makes their capture easy. On the mountain side above the town of Chamounix in France I found a shallow valley in which the finest of the European species (Parnassius apollo) was unusually common. From a seat on a stone high up in the middle of this valley I could see the butterflies zigzagging irregularly upward, flying back and forth across the valley as they came. As they ap- proached I could judge about where they would pass in their diag- onal flight and, by walking a few paces up or down, could easily intercept and capture them. If they are frightened they may make off at a very creditable pace, and then pursuit is all but hopeless. When depositing their eggs the females fly low with a curious slow, hesitating flight, and frequently alight upon the food plant. As a rule they are not shy, and are easily followed up and caught. Although nearly all of the parnassians are mountain butterflies, a few are found on the northern plains. They can withstand the most rigorous conditions on the high mountain peaks of central Asia and of Colorado, but none of them lives as far north as the Arctic regions. The farthest north that any has been found is Viliusk (lat. 63° 35’ N.) in the valley of the Lena River. Here Parnassius tenedius has been taken. This is not very far away from Verkhoyansk, the “cold pole” of the world, in the valley of the adjacent Jana River. One of the common European species (P. mnemosyne) ranges almost as far north. The butterflies of the far north and those of alpine regions are very variable from place to place and run into many puzzling forms, largely as a result of living in relatively small colonies in more or less widely separated localities. In the mountains the individuals of 290 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 a single species sometimes differ not only in adjacent valleys, but sometimes also in different portions of the same valley, or on differ- ent sides of the same peak. Probably all of the butterflies of the far north, and many of the alpine types as well, require 2 years, some possibly longer, in which to complete their transformations. Yet a few of the parnassians living high in the Himalayas in northern India have two broods a year. As a rule, arctic and alpine butterflies are smaller than their rela- tives farther south or in the valleys, and are also dingier or darker in color, at least on the under side. Their bodies and heads are very hairy. THE BUTTERFLIES OF SPRING Spring begins in earnest in the vicinity of Washington, D. C., about the middle of March. The conspicuous white flowers of the bloodroot appear in the woods above the carpet of fallen leaves. The leafy rosettes of the dandelions, the thistles, and the milfoil, bright green and fresh, are of good size, and the clovers, grasses, daisies, and other low-growing plants have put forth many bright ereen leaves. The trees as yet are leafless, but the elms, willows, alders, spice-bush, and some others are in flower. The cardinals, song-sparrows, robins, white-throated sparrows, mourning doves, and all of the smaller frogs are in full song, and the flickers and the phoebes are heard on all sides. Turtles are appearing on the logs and mud banks, reveling in the stimulation of the bright sunlight after the darkness of their long hibernation. At this time or some- what later in April, no less than 34 different kinds of butterflies are to be found upon the wing. These 34 species are divisible into four groups. The largest group includes 16 species all confined to North Amer- ica, but ranging widely throughout the continent. All of them live far to the northward, though only one, the yellow swallowtail (Pap- ilio glaucus) passes the Arctic Circle. All of these have at least two broods a year. The next largest group includes eight southern species, about half of which range southward into the Tropics. The most interesting in this group are the blue swallowtail (Papilio philenor), the zebra swallowtail (P. marcel/us), and the orange-tip (Anthocaris genutia). In this group falls the most brilliantly colored of all the local butter- flies, the lovely azure hair-streak (Strymon m-album). All but the orange-tip have at least two broods a year. The last has only a single brood in the vicinity of Washington, flying from March to early May; but in the cooler mountain regions farther south there are two ARCTIC BUTTERFLIES—CLARK 291 broods, one in early spring and one in early summer. Dr. W. J. Holland says that in the mountains of western North Carolina there is also an autumnal brood. The third group includes five butterflies of boreal, but not Arctic, range. These have only a single brood a year. The last group includes five species that range widely throughout the northern hemisphere. These are the mourning cloak (Aglais antiopa), the common blue (Lycaenopsis argiolus), the cabbage but- terfly (Pieris rapae), the small copper (Chrysophanus phlaeas), and the grizzled skipper (Pyrgus centaureae (pl. 6, figs. 51, 52)). All, with the exception of the last, have at least two broods a year. ALI of them range far to the northward into the Arctic, or at least high sub-Arctic regions. The common blue (Lycaenopsis argiolus), like the little copper (CArysophanus phlaeas), has an enormous range in both the New and the Old Worlds, and occurs in a bewildering array of local and seasonal forms, with many individual variants. The most interesting thing about the common blue in the present connection is that the early spring individuals captured in the vicinity of Washington resemble others caught in the far north near the Arctic Circle, where the butterfly has only a single brood. Later spring individuals resemble individuals of the summer brood in the most northern localities in which a summer brood occurs. But the mid- and late-summer forms are quite different from any of the forms found in the North. In the case of the little copper, the individuals that appear earliest in the spring have the fore wings much lighter in color and with smaller spots than those seen later, and the under side of the hind wings is darker. In other words, they show an approach to the far northern form fei/deni (pl. 6, figs. 49, 50), though the correspondence between the early spring and far northern individuals of the small copper is by no means so close as it is in the case of the common blue, where it amounts practically to identity. The same phenomenon is illustrated by the yellow swallowtail (Papilio glawcus). In this butterfly the earliest spring individuals are of the same size and color, with the same long hair on the head and body, as their representatives from farthest north. Indeed, some of the specimens from the vicinity of Washington taken in early spring are quite indistinguishable from others from north-central Alaska. No females have ever been found in early spring near Washington, and it is possible that here this form exists in the male sex only. It is perhaps to be expected that in butterflies ranging northward to Arctic or sub-Arctic regions the first individuals to appear in spring in the southern portion of the habitat should resemble those 111666—35——20 292 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 flying in summer farther north. But corresponding differences are found between the early spring and later individuals in butterflies that are wholly southern in their distribution. This is well illustrated by the zebra swallowtail (Papilio mar- cellus), of which the individuals flying in early spring are very small and very hairy, corresponding to the earliest individuals of the yellow swallowtail (P. glaucus). It is also seen in the blue swallowtail (P. philenor) in which the form found in early spring in the vicinity of Washington is very small and very hairy, with the light spots on the upper surface of the wings large and conspicuous. These early spring individuals of the blue swallowtail approach more or less closely the individuals of the Californian form (Azr- suta). With them there are occasionally found individuals of a tailless form (acauda) that are almost or quite identical with others from the hot lands of Mexico. Speaking of butterflies of hot lands and more or less arid regions, it may be mentioned that in all of our western and southwestern swallowtails (Papilio rutilus, P. daunus, and P. pilumnus) there is on the under side of the fore wings just within the outer border a broad, yellow, tapering band that takes the place of the row of spots seen in the common yellow swallowtail in summer. In the far north, in the high mountains of India and of central Asia, and in the vicinity of Washington in early spring the yellow swallow- tails (Papilio machaon and P. glaucus) all have this yellow band, just as do the arid country species. Speaking of these yellow swallowtails, it is of interest to note that our American yellow swallowtail (P. glaucus) in the far north flies together with the Old World swallowtail (P. machaon) both in the region of Hudson Bay and in Alaska. In the region about Hudson Bay the Old World species occurs in a form (hudsonzanus) that is scarcely different from the form found in northern Europe, but in Alaska the local form (a/éaska) is an offshoot from a group of similar forms living in the Himalayas and in the mountains of eastern Asia. In these two regions the local representatives of the American yellow swallowtail also show considerable differences. ANALYSIS OF THE ARCTIC BUTTERFLY FAUNA The outstanding and important characteristic of the Arctic archi- pelago, according to Prof. Robert F. Griggs, is its extreme dryness. The annual precipitation in all high Arctite countries is less than 10 inches, a deficiency in rainfall that in lower latitudes would invari- ably mark a desert. Middendorf long ago described the Siberian tundra as the most extreme desert, and said that it was too dry to be compared with any region familiar to Europeans. ARCTIC BUTTERFLIES—CLARK 293 In this connection the occurrence of the broad submarginal band on the under side of the fore wings in the Arctic yellow swallowtails as well as in all the yellow swallowtails of our more or less arid western country is of interest. Still more interesting is the occur- rence of the same band in the very small yellow swallowtails of early spring in the vicinity of Washington, together with the practi- cally tailless form (acauda) of the blue swallowtail (Papilio phil- enor) which is otherwise known only from Mexico and the southern portion of New Mexico. These occur, however, only if the warm weather of early spring follows immediately after very cold weather; if the passage of winter into summer is gradual they do not appear. All of the butterflies living about Washington that have both a “ wet ” and a “dry” form occur in early spring only in the latter. Such are the buckeye (Junonia coenia), the painted lady (Vanessa cardui), the anglewings (Polygonia) and the orange clover butterflies (Colas eurytheme). In the case of the buckeye and the painted lady the “wet ” form together with the “dry” is found in the late autumn, but only the “ dry ” lives through the winter. Among the most char- acteristics of the Arctic butterflies are the clover butterflies (Colzas), the bog fritillaries (Brenthis), the little blues (Lycaenidae), and the satyrids (Satyridac). In the arid regions of the Tropics we find as characteristic butterflies close relatives of the clover butterflies (espe- clally Catopszlia), various little blues, and certain satyrids. Further- more, some of the bog fritillaries live in regions that for a large por- tion of the year are extremely dry. Professor Griggs has pointed out that the floral characteristics of the Arctic are chiefly negative, owing to the absence from northern lands of species occurring in southern latitudes. This is quite as true of Arctic butterflies as it is of Arctic plants. Although all Arctic plants are more or less dwarfed and usually rise but little above the ground, they exhibit no structural peculiari- ties that differentiate them from allied species farther south. Among the butterflies all the Arctic species or varieties are more or less dwarfed, but they show no structural differences as compared with others from other regions. In addition to being dwarfed they are more or less suffused with black or blackish, at least on the under side, and the head and body are very hairy. These features are shared with early spring butterflies from regions much farther south, es- pecially in eastern North America. One of the clover butterflies in the vicinity of Washington (Colias eurytheme) in early spring ap- pears in a small and very pale form with only a slight trace of orange on the upper side, and dark greenish on the under side of the hind wings. In autumn, if the season be hot and dry, this small light form reappears, but without the dark suffusion on the under side. 294 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 Sir Joseph Hooker wrote that “of the plants found north of the Arctic Circle very few are absolutely or almost confined to frigid latitudes (only 50 out of 762 or so); the remainder, so far as their southern distribution is concerned, may be referred to two classes; one consisting of plants widely diffused over the plains of northern Europe, Asia, and America, of which there are upwards of 500; the other of plants more or less confined to the alps of these countries, and still more southern regions, of which there are only about 200.” Essentially the same is true among the butterflies. Professor Griggs has written that the vegetation of the Arctic re- sembles most closely that of waste lands—the vegetation of recently ploughed fields, earth slides, freshly exposed gravel banks, etc. “ Such common weeds as the sheep sorrel, the common horsetail, chickweed, winter cress, rib grass, Kentucky blue grass, cuckoo flower, tall but- tercup, fireweed, and Rhode Island bentgrass range far north in the Arctic, some of them to the north coast of Greenland.” The general aspect of the Arctic butterfly fauna is very much the same. ‘The butterflies of the Arctic are representatives of types that are elsewhere characteristic of rough and forbidding country, waste lands, or more or less arid regions, or at least that occur in such un- favorable situations. EXPLANATION OF PLATES (All of the specimens figured are in the collection of the United States National Museum ) PLATE 1 Fiaure 1. Brenthis frigga, Tornea, Finland (Barnes collection). . Same, under side. . Brenthis freija, Helsingfors, Finland (Barnes collection). . Same, under side. . Brenthis chariclea montinus, Mount Washington, New Hampshire (Barnes collection). Same, under side. . Brenthis chariclea arctica, Greenland (Barnes collection). . Same, under side. . Brenthis aphirape triclaris, Atlin, northern British Columbia (Barnes collection). 10. Same, under side. Om © ND OMWAD PLATE 2 Ficurn 11. Brenthis frigga saga, Kettle Rapids, Nelson River, on the Hudson Bay Railroad, July 8, 1914 (Barnes collection). 12. Same, under side. 13. Brenthis polaris, Okak, Labrador, August 16, 1923 (Barnes collec- tion). 14. Same, under side. Figure 15. Ficure 21. 22. ARCTIC BUTTERFLIES—CLARK 295 Brenthis improba, Bernard Harbor, Arctic coast of North America, Northwest Territory; Canadian Arctic Expedition; Fritz Johann- sen, July 1916 (Barnes collection). . Same, under side. . Brenthis pales, Albula Pass, Upper Engadine, Switzerland (Barnes collection). . Same, under side. . Brenthis pales alaskensis, Alaskan Arctie coastal plain, lat. 69° N. (Barnes collection). . Same, under side. PLATE 3 Brenthis cytheris falklandica, Port Stanley, Falkland Islands; col- lected by Karl Vernon Lellman for Dr. Waldo L. Schmitt. Same, under side. . Brenthis cytheris, male. . Same, under side. . Brenthis cytheris, female (W. Schaus collection). . Same, under side. . Cosmosatyrus chiliensis. 28. Same, under side. FIGURE 31. 32. 34. 35. 36. ot. 38. FIGurE 39. 40. 41. 42. 43. 44, 45. 46. . Erebia vidleri, Lalood, British Columbia, 4,500 feet altitude, July 14, 1916 (Barnes collection). . Same, under side. PLATE 4 Colias lesbia, male, La Rioja, Argentina, EH. Giacornelli. Colias lesbia, female, Montevideo, Uruguay, J. Felippone. Colias hecla, male, Greenland, M. Bartel (Barnes collection). Colias hecla, female, Umanak, Greenland, July 21, 1914 (Barnes collection). Colias pelidne, male, Okak, Labrador, August 16, 1923 (Barnes col- lection). Colias nastes, female, Wilcox Pass, Clark, July 1930 (Barnes col- lection, from the Oberthtir collection). Colias palaeno, male, Gellivare, Lapland, Sweden, M. Bartel (Barnes collection ). Andina huanaco, male, Bolivia (Neumdgen collection). PLATE 5 Oeneis jutta, female, Passaduinkeag, on the Penobscot River about 30 miles north of Bangor, Maine, July 11, 19838 (Barnes col- lection). Oeneis katahdin, Mount Katahdin, Maine, H. H. Newcomb, June 29, 1901 (Barnes collection, through P. G. Bolster). Oeneis jutta; under side of the specimen shown in figure 39. Oeneis katahdin; under side of the specimen shown in figure 40. Oeneis melissa semidea, Alpine Gardens, Mount Washington, N. H., 5,000 feet altitude (Barnes collection). Same, under side. Tatochila xanthodice, male, Tarqui, Ecuador, F. Campos. Tatochila ranthodice, female, Ecuador (Neumégen collection). 296 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 PLATE 6 Ficure 47. Plebeius orbitulus, Atlin, northern British Columbia (Barnes collec 48. 49. o4, FIGurE 55. 56. tion). X<1%. Same, under side. X1%. Chrysophanus phlaeas feildeni, McCormicks Bay, Smith Sound northwestern Greenland, August 4, 1892 (Barnes collection). x11. . Same, under side. X1%. . Pyrgus centaureae, Paterson, N. J., April 16 (Barnes collection). x1. . Same, under side. X1%. . Huchloé creusa, Atlin, northern British Columbia (Barnes collec- tion). Natural size. Same, under side. Natural size. PLATE 7 Parnassius apollo hesebolus, male, Kuldja, Ili Province, Sungaria (Neumodgen collection). Parnassius discobolus, female, Kuldja, Ili Province, Sungaria (Neumogen collection). PLA es 1 Smithsonian Report, 1934.—Clark ARCTIC BUTTERFLIES. (For explanation see page 294.) PEATE 2 Smithsonian Report, 1934.—Clark ARCTIC BUTTERFLIES. (For explanation, see page 294.) PLATE 3 Smithsonian Report, 1934.—Clark ARCTIC BUTTERFLIES. (For explanation, see page 295.) Smithsonian Report, 1934.—Clark PLATE 4 ARCTIC BUTTERFLIES. (For explanation, see page 295.) Smithsonian Report, 1934.—Clark PIEASEw) ARCTIC BUTTERFLIES. (For explanation, see page 295.) Smithsonian Report, 1934.—Clark ARCTIC BUTTERFLIES. (For explanation, see page 296.) Smithsonian Report, 1934.—Clark ARCTIC BUTTERFLIES. (For explanation, see page 296.) GRASSES, WHAT THEY ARE AND WHERE THEY LIVE By A. S. HitcHcock Principal Botanist in Charge of Systematic Agrostology, United States Depart- ment of Agriculture [With 8 plates] The flowering plants of the world are divided among about 300 families. Of these the grass family (Gramineae or Poaceae) is the most useful to man. From the botanical standpoint grasses are plants which possess certain structural characteristics that differen- tiate them from other families. The grasses were recognized as a natural group long before there was a science of botany or a system of classification, just as palms, cactuses, and legumes were recog- nized as plant families even by primitive peoples. Our common meadow, pasture, and lawn grasses, such as timothy, redtop, blue- grass, and Bermuda grass, are known to nearly everyone. Many people also know as grasses the numerous wild prairie grasses and such common weeds as crabgrass and quackgrass. But it is news to some that the grass family includes the grains or cereals, such as wheat, oats, rye, barley, corn (maize), and rice, as well as sugar- cane, sorghum, and millet, and the woody-stemmed bamboos. Those who are not very discerning may include among the grasses other plants with long narrow leaves, such as sedges, rushes, and even narrow-leaved lilies. The tendency to include the term grass as a part of the common name of plants, other than grasses, having nar- row leaves, is shown by such names as beargrass (Xerophyllum tenax), a kind of lily, common in our Northwestern States; blue- eyed-grass (species of Stsyrinchium), small plants of the iris family ; ribgrass (Plantago lanceolata), a narrow-leaved plantain; eelgrass (Zostera marina), a submerged plant of the pondweed family grow- ing along our coasts; sawgrass (Mariscus or Cladium), a large sedge with vicious saw-edged leaves, especially abundant in the Florida everglades; and stargrass (Wypowis), of the amaryllis fam- ily, with small yellow flowers. 297 298 § saNNUAL REPORT SMITHSONIAN INSTITUTION, 1934 To the farmer or stockman grass may mean almost any herbaceous plants upon which animals graze, including clovers, alfalfa, and other legumes. Indeed, the English word grass is derived from the same root as graze, grass being the principal part of grazed herbage. STRUCTURE The structures which the various grasses have in common and which together distinguish them from other families are the jointed stems, hollow as in wheat, or pithy with solid joints or nodes as in corn and sorghum; leaves alternate in two ranks, and consisting of two parts, the sheath and the blade, the sheath surrounding the stem like a tube, the blades diverging more or less. Any plant with such a stem and such leaves is a grass. INFLORESCENCE The inflorescence or flowering part of grasses is borne at the top of the stem or at the ends of the branches. The flowers are borne in the axils of bracts on minute specialized branchlets called spike- lets. The flowers are inconspicuous, without calyx or corolla. They consist of a single pistil with a one-celled ovary, two styles with feathery stigmas, and usually three stamens. Each flower is borne between two small green bracts. The ripened ovary, the grain, has a small embryo and a large mass of starchy endosperm. The “ germ ” of a kernel of corn is the embryo; the rest of the kernel is endosperm. At the base of the spikelet are two empty bracts, the glumes. These are very large in the oat, and minute in bluegrass. The spikelet may contain a single floret (the flower with its two bracts) as in redtop and timothy; two or three as in the oat, or several to many, as in bluegrasses, fescues, and brome grasses. The florets, like the leaves on the culm, are always two-ranked. If we examine a head of wheat we find a central flat zigzag axis with spikelets about half an inch long in an overlapping row on each side. In bearded wheats the spikelets bear long awns or bris- tles. Each spikelet contains several bracts (in rows), within which are the flowers as described above. The form of the inflorescence in grasses is very diverse, and it is this which gives the characteristic aspect to the different species. Barley and rye have heads or spikes like wheat. In oats the large spikelets are borne on long pedicels in an open panicle. In redtop, bluegrass, and the fescues the spikelets are borne in rather loose panicles, whereas in timothy the panicle branches and pedicels are so short that the spikelets are closely packed in a cylindrical head or spike. In sugarcane, giant reed (Arundo), and pampasgrass (Cortaderia) there is a large number of spikelets in a great feathery GRASSES—HITCHCOCK 299 mass or plume. In crabgrasses (Digitaria), Bermuda grass (Cynodon), and goosegrass (leusine) the spikelets are borne in slender one-sided digitate (fingerlike) spikes. Most grasses have perfect flowers (stamens and pistils in the same flower). Those with unisexual flowers (containing only stamens or only pistils) may be monoecious (the two kinds of flowers on differ- ent parts of the same plant, as in corn) or dioecious (the two kinds of flowers on different plants, as in buffalo grass (uchloé) and saltgrass (Distichlis) ). POLLINATION Basically, the pollination and fertilization of grasses is the same as in other kinds of flowering plants. The pollen produced by the stamens is transferred to the stigmas of the pistil, the process being called pollination. There the pollen germinates and (by means of a minute tube) grows down through the style into the ovary and finally to the germ cell of the ovule. The protoplasm of the end of the pollen tube fuses with the protoplasm of the germ cell, fertilizing it. The fertilized ovule develops into a seed. (See p. 298.) Showy or fragrant flowers are chiefly pollinated by insects, which, seeking nectar, become covered with pollen in one flower and carry it to the next one visited, where some of it is dusted on the stigmas. Darwin and others have shown that cross-fertilization as a rule produces more vigorous offspring than does self-fertilization. The means by which cross-pollination is effected in plants is of great interest, and many botanists have given much time to its study. Grasses may be cross-pollinated or self-pollinated. The latter process is more common in grasses than in most other plants. (See p. 300.) For cross-pollination the grasses depend largely on the wind, which, however, is so wasteful of pollen that, as in all wind-pol- linated plants, the amount produced is greatly in excess of the amount used. The wind must carry clouds of pollen in order that a few grains may reach the stigmas (only one grain being needed for the fertilization of an ovule). This over-production of pollen of grasses and some other wind-pollinated plants, especially ragweed, afflicts man with the so-called “ hay fever ”. There are among the grasses certain habits or structures which favor cross-pollination. In dioecious grasses self-pollination cannot occur. In monoecious grasses cross-pollination is the rule, though self-pollination is possible. The corn plant is a familiar example of the effect of the separation of the sexes on the same individual (monoecism). Under cultivation corn is grown in large areas. The wind carries the pollen from the tassels of one group of plants to the silk of plants lying to the leeward of these but allows little to 300 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 settle on the silk of the same plants that furnish the pollen. How little naturally falls in this way is shown by the comparative sterility of single isolated stalks. The cob of such plants usually bears only a few seeds or grains. POLLINATION OF BLUE GRAMA Grasses with perfect flowers may show adaptations that aid in cross-pollination. A common grass of the Great Plains known to stockmen as blue grama (Bouteloua gracilis) illustrates one of these adaptations. The inflorescence consists of two 1-sided spikes at- tached obliquely at the upper part of a slender stem about a foot tall. The spikes or flags are about an inch long and an inch apart on the stem. When the wind blows, the spikes are thrown to the lee side. The spikelets are close together on the axis of the spike. At the time of flowering (at anthesis, the botanist would say) the anthers are exserted to leeward on slender filaments. The two feathery stigmas are also exserted but on the windward side. This arrangement practically compels cross-pollination. All the pollen is carried away from the stigmas of the same plant, whereas the stigmas must receive pollen from some other plant. SELF-POLLINATION It is probable that many grasses are self-pollinated if cross-polli- nation fails. Wheat, for example, opens and exposes the anthers and stigmas for only about 15 minutes in the morning. During this time cross-pollination may occur. Some grasses appear to depend mainly on self-pollination, in which case much less pollen is necessary than in the case of cross-pollinated plants. But continued self-pollination (inbreeding) may result in deterioration. Some kinds of grasses produce flowers that are normally self- fertilized (cleistogamous flowers). One such kind, a rather rare species (Amphicarpum purshii) grows in sandy soil of the Coastal Plain from New Jersey to Georgia. It bears a terminal panicle with perfect flowers, but these appear to be normally unfruitful— why, is not at present known. On slender subterranean branches from the base of the plant are borne single large fruitful spikelets that never open, being fertilized by the pollen of their own minute anthers. There are a few other species, curiously enough all Ameri- can, with similar subterranean cleistogamous spikelets. An example of another kind of cleistogamy is furnished by poverty oatgrass (Danthonia spicata), frequent in the eastern United States on sterile soil. The terminal panicle bears a few large spikelets, each with several florets. Hidden in the sheaths at the base of the stem GRASSES—HITCHCOCK 301 are self-fertilized cleistogamous spikelets of a single large floret with larger grains, quite different from those of the terminal panicle. At maturity the stem, with its sheath and enclosed grain, disjoints at the node below and can be blown about by the wind. The num- ber of species known to produce cleistogamous spikelets in the lower sheaths is constantly increasing as attention is given to the subject.’ VEGETATIVE PROPAGATION Propagation of grasses may be by seed or by various vegetative methods. Annuals depend absolutely on their seeds for the con- tinuation of the species. Perennials are less dependent on seeds since the individual may survive indefinitely. In a general way the perennial grasses may be divided into two groups, the tufted kinds that form crowns, and those that spread by means of rhizomes or stolons. Rhizomes or rootstocks are creeping underground stems, from the nodes of which upright shoots are produced thus establishing new plants which in turn form more rhizomes. Such plants are likely to be gregarious. They are found mostly in loamy, sandy, or muddy soil where the rhizomes meet with little resistance. In marshes they are constantly extending on the water side and retreating on the land side. The thick growth of the stems allows the deposit of additional material, thus building up soil from the bottom. Finally, the conditions on the land side are less favorable to the growth of the species, and it fails to withstand the competition of other species. Meantime the marsh is being converted into dry land. SAND-BINDERS Other rhizomatous species are at home on sand dunes. The best known of these dune grasses is the beachgrass (Ammophila arenaria) of Europe, where it is planted extensively to hold drifting sand along the coast. The region now occupied by Golden Gate Park, San Francisco, was once a sterile waste of sand such as is seen along the coast to the south. Beachgrass was imported and set out to hold the sand. After the sand had been fixed by the grass, trees were planted, the soil was enriched, and there has gradually emerged the beautiful park we see there now. Along the sandy coasts of Europe beachgrass is planted to form the great barrier dunes that protect the land behind. Trees are grown in the lee of the dune, but these cannot withstand the severe conditions of the dune on the side toward the sea. The barrier dunes 1Those interested may consult an article entitled “Axillary Cleistogenes in some American grasses”, by Agnes Chase, Amer. Journ. Bot., vol. 5, p. 254, 1918. 302 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 are constantly guarded to repair the inroads of the sea during storms. In southwestern France there is a region which consisted formerly of alternating sand hills and marshes ill-fitted for agriculture and sparsely populated. This area, called the “ landes,” lies between the Gironde River and Bayonne. Beachgrass was planted and supple- mented by brush fences to hold the sand. In due time a long barrier dune was built up which protected the region behind. In the lee of the barrier dune a forest of pines was produced. Since the reclama- tion the conditions have so changed that the population has very materially increased. In the Netherlands a line of dunes extends all along the coast of the provinces of North Holland and South Holland. These are two of the richest provinces in the kingdom, and it is very important to prevent the encroachment of the sea upon the agricultural lands which lie just back of the coast. Beachgrass plantings on the exposed sea- ward side of the dunes prevent the sand from being blown inland, and forests are planted on the lee side. Other important reclamation work by means of beachgrass has been done in Denmark, especially on the north coast near Skagen, and in Germany on the Baltic coast. Especially impressive is the work done on the Kurische Nehrung in northeastern Prussia. This nar- row sandpit (60 miles long) protects the harbor of the Kurisches Haff, on the east side of which lies Memel. This harbor was formerly endangered by the encroachment of the shifting sand from the dunes. Here again the dunes were fixed with beachgrass, and later all except the exposed sea slope was planted with trees. Our American species of beachgrass (Ammophila breviligulata), found along the Atlantic coast as far south as North Carolina, and around our Great Lakes, is similar to the European species and has been used for holding dunes on Cape Cod and along Lake Michigan. Beachgrass not only has numerous and vigorous rhizomes but also stems which grow upward as the sand accumulates, never becoming buried. COASTAL SALT MARSHES Salt or brackish marshes along the seacoast are made up largely of rhizome-bearing grasses. The plants, of course, will not withstand the battering of the surf, but in the quiet waters of bays and inlets they thrive wherever the rise and fall of the tide is not too great, and where the bottom is sand or mud. Large areas may be occupied by a single species (notably species of Spartina, or cordgrass), the rhi- zomes being so interlaced and so fully occupying the soil that no other kind of plant can gain a foothold. GRASSES—HITCHCOCK 303 A notable example of the conversion of shallow water of salt marshes ultimately into dry land is seen on the southern and eastern coast of England, and the continental coast opposite, where Spar- tina townsendii (called “ rice grass” in England) has been planted. Great areas are thus being reclaimed from the waters of bays and estuaries. At first there was a fear that the grass would stop up the channels in the harbors and interfere with navigation, but it was soon found that the grass could not grow in deep water; it was therefore an aid to navigation rather than a hindrance. Throughout our inland regions shallow lakes are being converted into marshes, and these into dry land, by various water plants, prominent among which are grasses (species of Calamagrostis, Leer- sia, and Glyceria are especially effective). WEEDS WITH RHIZOMES Several species of rhizomatous grasses become troublesome weeds. Not only do the plants spread rapidly by the rhizomes, but cultiva- tion serves to propagate the invader, since every joint left in the soil starts a new plant. Quackgrass (Agropyron repens), introduced from Europe, is an example of this group. Johnson grass (Sorghum halepense), intro- duced from the Mediterranean region, is a great pest in our Southern States because of its strong rhizomes. It has one mitigating char- acter, it is good for forage. Johnson grass was originally intro- duced for forage, but because of its aggressiveness in invading culti- vated fields it lost favor with planters in the South. It is now used for forage chiefly in fields that have become so badly infested that they cannot be profitably put to cotton or other cultivated crops. Bermuda grass (Cynodon dactylon), also from the Medi- terranean region, is a good pasture grass but a bad weed in cotton fields. STOLONIFEROUS GRASSES Several grasses propagate by creeping stems above ground, called stolons. Buffalo grass (Buchloe dactyloides), dominant over much of the northern and central part of the Great Plains, once formed hundreds of miles of turf, supporting countless herds of bison. Its tough sod, held together by interlacing stolons, was used by the early settlers for making sod houses. In Texas another stoloniferous grass (Zilaria belangeri) is dominant on the plains. Rhodes grass (Chloris gayana), a forage grass of Arizona, introduced from Af- rica, produces hard stolons several feet long with internodes as thick us a pipestem. 304 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 TUFTED GRASSES Grasses without rhizomes or stolons grow in tufts, the new shoots arising erect beside the old ones. Such tufts increase in diameter by this gradual accretion at the periphery. If the tufts are very compact the center ultimately dies, since the closely pressed old growth allows no new shoots to appear. There are several grasses on the Great Plains that form such close, regular, circular tufts that they produce “ fairy rings.” The ring may expand to a diameter of several feet, with a fairly regular border of living plants. For some time the center is so full of old roots and the bases of stems that other plants can get no foothold. Eventually the crowded cen- ter dies out, and after many years the ring begins to break up. One then sees a more or less definite circle of tufts among other grasses which meantime have become established. It is probable that some of these rings are more than 100 years old. SEEDS OF PERENNIAL GRASSES On the whole, grasses that propagate vegetatively produce a rela- tively small amount of fertile seed. In some species the power to produce viable seed has been almost lost. This is especially true of sugarcane, the only important cultivated perennial grass that is used for food. The large panicles or plumes contain innumerable flowers but few fertile seeds. Until recently the species was thought to have been cultivated so long by vegetative methods that it had lost the power of producing seed. It is now known that occasional seeds are found, and it is these that are used in obtaining new varieties. By planting a whole plume it is found that now and then seedlings appear. SEEDS OF ANNUAL GRASSES Annuals, on the other hand, necessarily produce an abundance of good seed. This is why primitive man chose annual grasses to culti- vate for food. All our cereals are annuals, improved by long selec- tion. Perennial grasses that are normally poor seed-bearers could probably be improved by breeding and selection. ‘Timothy, a peren- nial meadow grass, produces an abundance of good seed. This is one reason why timothy is a leading commercial grass. The life histories of annuals and perennials differ widely. Annuals depend upon wide dissemination of abundant viable seed to maintain their existence. The seed must be deposited in a favorable situation, must retain its viability, sometimes for long periods, and must ger- minate quickly under favorable conditions. Therefore, annuals are found primarily in open ground, cultivated fields, soil thrown up by burrowing animals, and in newly formed soil of any kind. Annuals GRASSES—-HITCHCOCK 305 quickly appear in openings in timber due to fire, to landslides, or to other agencies that destroy the trees previously occupying the space. Banks of rivers or sandbars exposed by receding waters are soon occu- pied by annuals. Sandy soil in regions of moderate rainfall also fur- nish a satisfactory substratum for them. When the sand is wet, the seeds germinate quickly, and the plants are often able to produce their own crop of seed before the soil dries out. In desert regions annuals spring up quickly after a rain and mature seed before the effects of the rain have passed. “ Six-weeks ” grasses of several annual species are abundant after rains in the arid regions of our southwestern States. PERENNIALS MORE PERSISTENT THAN ANNUALS Perennials come to maturity more slowly than do annuals and usually do not produce seed the first year. But once established they can hold the ground against annuals. The difficulty of keeping crab- grasses out of lawns composed of perennial grasses may seem to con- tradict this statement. But a lawn, except in a region of plentiful fogs and drizzle, is a highly artificial creation. The frequent mowing weakens the plants, for it is the foliage that makes the food, and the constant watering causes the roots to spread close to the surface in- stead of deep into the soil. When crabgrass and yellow bristlegrass take possession of a lawn it is because the perennials fail to withstand the hard conditions and leave unoccupied spots. The countless seeds of annuals are ever present to take advantage of any opening. GRASSES A DOMINANT FAMILY Grasses are one of the dominant families of plants. In number of genera and species they are exceeded by the sunflower family (Compositae), the orchids, the legumes, and the madder family (Ru- biaceae), but in the number of individuals they probably exceed all other families. They are distributed throughout the world, from pole to pole, and from sea level to alpine summits, wherever there is a substratum (free from snow for a part of the year) on which they can grow. Only in tropical rain forests are they scarce. Here are found several species with broad thin blades that are able to grow in the deep shade. But even in the rain forests narrow-leaved grasses grow in the occasional openings where the light is more abundant. In the American tropical rain forests there are several kinds of climbing bamboos forming beautiful lacy curtains along trails and streams. Grasses vary in size from an inch to 100 feet or more (giant bam- boos). They may be erect, creeping, or climbing. The climbing species have no special organs, such as tendrils, nor do they twine. 306 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 However, certain species, especially the so-called “climbing bam- boos ”, reach up through the foliage of trees much as do some kinds of brambles. The stems are prevented from slipping back by rather stiff horizontal or reflexed branches. The grass family is adapted to a great variety of soils. The species are found in salt- and fresh-water marshes, and in sand, as already described, on rocks, and even in alkali wastes. The ordinary meadow grasses grow on moderately dry soil, receiv- ing a medium rainfall. Here grow our familiar cultivated species, Kentucky bluegrass (Poa pratensis), redtop (Agrostis alba), timothy (Phleum pratense), orchard grass (Dactylis glomerata), meadow fescue (Festuca elatior), Bermuda grass (Cynodon dactylon), and others. The species may be sod-formers (with rhizomes) or bunch grasses (without rhizomes). Of those mentioned above, Kentucky bluegrass, redtop, and Bermuda grass have rhizomes; the others do not. DISTRIBUTION The distribution of grasses in the United States depends largely upon rainfall and temperature. The region from the Atlantic Coast to eastern Nebraska and Texas usually receives sufficient rainfall to produce staple crops, such as corn, wheat, and cotton, and the common meadow and pasture grasses, such as timothy and bluegrass in the North and Bermuda grass in the South. In a general way this area is called the humid region. There is another humid region in the northwestern States from northern California (west of the Sierras) to British Columbia, and east to the Cascades. There are also many small humid valleys in all the western mountain ranges. Much of the humid region in the East was originally covered with forest. But in the northern and western part there were more or less extensive grasslands called prairies. For example, much of northern Illinois and Iowa was prairie, and the western fringe of the humid region passed gradually from prairie to the vast treeless expanse of the Great Plains. The wild grasses of the prairie are rather tall species, partly rhizomatous, partly bunch grasses, such as bluejoint turkeyfoot, some- times called bluestem (Andropogon furcatus), prairie beardgrass or little bluestem (A. scoparius), Indian grass (Sorghastrwm nutans), and switchgrass (Panicum virgatum). The region between the Mississippi River and the Rocky Moun- tains becomes increasingly dry toward the west. This, the Great Plains, is a dry, nearly level area, increasing in altitude from 1,000 feet to about 6,000 feet at the foot of the mountains. The approxi- mate line of demarkation between the prairie region and the Great GRASSES— HITCHCOCK 307 Plains is the 100th meridian. The annual rainfall for the Plains varies from about 28 inches on the east to 16 inches on the west. The erasses of the Great Plains are known as “short grasses” to distin- guish them from the “ tall grasses” of the prairies. The dominant grass over much of this region is buffalo grass (Buchloé dactyloides), mentioned on page 303. In Texas Buffalo grass is partially or wholly replaced by curly mesquite (Hélaria belangert). Blue grama (Bou- teloua gracilis) and black grama (B. hirsuta), both bunch grasses, are also abundant throughout the Great Plains and are excellent forage grasses. The Great Plains, which extend beyond the boundaries of the United States, far northward into Canada, and southward to merge with the Mexican Plateau, form one of the great grass regions of the world. Other important comparable grasslands are to be found in the llanos (Spanish for plains) of northern South America, the pampas (another Spanish word for plains) of southern South Amer- ica, the steppes of European and Asiatic Russia, and the high plains of Africa extending from Kenya to Rhodesia. In the Great Basin, between the Rocky Mountains and the Sierra Nevada, there are large areas with scant rainfall (mostly less than 16 inches annually). These areas are semiarid; or, if the rainfall is very low and the temperature high, they are classed as deserts. ‘The culmination of aridity is found in the Colorado Desert of the lower Colorado River Valley, and the Mohave Desert (including Death Valley) lying to the north. In this desert region the rainfall is mostly below 8 inches. The grasses of the Great Basin are mostly in widely scattered bunches of highly drought-resistant species of the genera Bouteloua, Aristida, Sitanion, and Stipa. ALKALI GRASSES There are many areas, especially in the drier regions of the United States, where the soil is so strongly impregnated with soluble salts (alkali) that, even though moist, vegetation is more or less inhibited. Only plants resistant to alkali can thrive under such conditions. As the soluble salts of the soil increase, the number of species dimin- ishes until a point is reached where no vegetation can exist. ‘These salt or alkali (often soda) deserts are found around salt lakes (such as Great Salt Lake) or depressions that are shallow lakes after rains, The characteristic grasses of such regions not so strongly alkaline or saline as to inhibit vegetation are species of saltgrass (Distichlis), alkali-grass (Puccinellia), and alkali sacaton (Sporobolus airoides). 111666—35——21 308 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 When the alkali is too strong for vegetation of any kind, the glaring white, usually rather smooth area is colloquially known as a “ slick desert.” Salt lakes, salt basins, and alkali depressions are produced by the evaporation from undrained areas. The more soluble salts are dissolved in the soil water during wet periods and left on the surface by evaporation during dry periods. Certain faulty agricultural practices in irrigated regions illus- trate the artificial production of alkali-meadows. In the early days where water for irrigation was plentiful, the ranchmen often allowed an excess of water to flow over meadows to encourage the growth of erass or alfalfa. Unless there was good drainage the soaking brought soluble minerals from below and deposited them at or near the surface as the water evaporated. As the meadows became more and more alkaline the desirable plants gradually disappeared, their place being taken by species more resistant to alkali but less valuable agriculturally. This alkaline condition can be prevented by proper drainage and by supplying water in only such quantity as is nec- essary. VARIATION IN LEAF STRUCTURE The structure of grasses varies with the necessity for resisting evaporation. In regions of abundant rainfall throughout the grow- ing season the grasses have abundant foliage and mostly flat leaf- blades. Of course, the plant must obtain the necessary minerals from the soil by an upward current from the roots. Evaporation from the leaves draws the soil water upward. If the supply of water from the soil does not balance the evaporation from the leaves, the plant wilts. Even in humid regions there is variation in the proportion between absorption and evaporation. Normally, the leaves meet this variation through control of the stomata or breath- ing pores, which are mostly on the under surface of the blades. These close when the air is dry and open when it is moist. If the conditions are such that the grasses have difficulty in ob- taining from the soil the necessary water, the leaves are structurally different from those grasses that grow in a humid climate. The epidermis is thick and impervious to moisture, so that evaporation takes place only or chiefly through the breathing pores. The blades are often tightly rolled with the breathing pores on the inside. The leaves may be short and clustered close to the ground. In extremely dry regions the plants retreat underground for protection during the dry season, as do herbaceous perennials in winter in humid re- gions. Life persists in the perennial base beneath the surface ready to send forth shoots after a rain. GRASSES—HITCHCOCK 309 Grasses of high altitudes and high latitudes have leaf structures similar to those of desert grasses. The water supply may be ample, but the low temperature of the water and often also of the air inter- feres with water absorption. The leaves thus have a structure that reduces evaporation to correspond to water supply. Even in humid regions the water supply may be reduced on rocks or sand, and grasses growing on rocky or sandy soil may have the structure of dry land grasses. ‘The grasses of salt meadows or marshes also have structures that reduce evaporation to meet re- duced absorption by the roots. The absorption of soluble salts is hindered more and more as the concentration of the soil water increases, SEED DISPERSAL Grasses owe their dominance to their ability to make a living under all conditions where the higher plants can live at all, and also to their ability to reproduce themselves and spread their seeds far and wide. The seeds are often provided with special structures that aid in their dissemination. The means of dispersal are chiefly wind and animals, though water may play a minor part. Small seeds may be carried by wind great distances without especial adaptive attachments. Some seeds in- crease their chances of dispersal by wind by having outgrowths of hairs or fuzz. Such seeds are able to remain longer in the air and can be carried further in proportion to their weight than can naked seeds. Examples of this are broomsedge (Andropogon), plumegrass (Lrianthus),and reed (Phragmites). The long spreading or reflexed awns of certain species of Avistida aid in wind dispersal. On the Great Plains the seeds of A. longifolia and allied species may be seen drifting across the surface of the soil in countless numbers. The three spreading awns give a surface upon which the wind acts. TUMBLEWEEDS This adaptation to wind dispersal is further developed in tumble- weeds. In a typical tumbleweed the whole plant at maturity is a more or less globular mass of hard stiff branches. The stem breaks off near the ground and the whole plant goes tumbling and rolling before the wind, scattering seed as it goes. Tumbleweeds are charac- teristic of prairies and plains, as they can function only in open ground. In grasses it is only the inflorescence that acts as a tumbleweed. Witchgrass (Panicum capillare) and ticklegrass (Agrostis hiemalis) are examples. At maturity the panicles with their stiff, slender, spreading branches become light, open skeleton balls which break away and roll before the wind. 310 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 DISPERSAL BY ANIMALS Many grasses are adapted to dispersal by animals (including man). The seeds of this class have a covering or appendage which sticks to the wool, hair, or fur of animals, or to the clothing of man. The familiar sandbur has barbed spines for the purpose of attach- ment. Needlegrasses (Stipa) and three-awns(Avristida) have seeds with sharp, barbed points that penetrate wool or clothing. The base of the spikelets of Bromus rigidus (called ripgut grass by stockmen) is sharp and barbed. The seeds penetrate wool and, much worse, get into the eyes and nostrils of grazing animals, causing serious injury to stock in western States where the grass is often abundant. DISPERSAL OVER TRADE ROUTES The methods of dispersal described above account for the spread of species in rather restricted areas. We find, however, that certain kinds of plants, known as weeds, travel widely over the earth. The spread of such plants has been greatly expedited during the last few hundred years. The more rapid rate of travel coincides with the development of the means of transportation by man. Many plants, grasses among them, have been carried along the channels of trade through the agency of man. Some seeds have been carried entirely by accident; others have been carried as impurities in agri- cultural seed, accidentally, to be sure, but as a part of a direct inten- tion. Bluegrass (Poa pratensis) is not a native of the United States but is now so widespread that, did we not know its history, it would be assumed to be native. From time to time noxious weeds have suddenly appeared in interior States, brought in along with im- ported seed of alfalfa, cereals, or meadow grasses. When such chance introductions have found favorable conditions for their growth, they have spread and not infrequently have become a menace to crop plants. USES OF GRASSES From the standpoint of mankind the primary uses of grasses are as food for man and feed, fodder, or grazing for domestic animals. The grasses furnishing food for man are the cereals, the most important of which are wheat, corn (maize), rice, barley, rye, and oats. In earlier days other grasses were used, such as millet (Seta- ria), Sorghum, African millet (Zleusine), broomcorn millet (Pani- cum miliacewum), Japanese millet (Hchinochloa), pearl millet (Pennisetum), tefl (EHragrostis abyssinica), certain of the wheat genus (emmer, einkorn, and spelt), forerunners of our modern cul- tivated forms, and other less familiar grasses. Many of these food GRASSES—HITCHCOCK 311 grasses are still in use among primitive peoples. All the species mentioned are annuals and the part used is the seed. When animals were first domesticated by man in prehistoric times, they depended upon native pasture land for sustenance. Though cattle may graze upon a variety of plants, by far the most important element of pasture lands is the grasses. Only within the last 2 or 3 centuries have grasses been grown for pastures and meadows by sowing the seed of definite species. The seed of many of the cereals is used for stock feed, the most important being corn and, mostly for horses, oats. Corn, of American origin, is now widely cultivated throughout the world. An important noncereal grass, sugarcane, furnishes food for man, but in this case the juice of the stem is used. This is the only im- portant perennial agricultural food grass. Sugarcane has come into world-wide prominence only within comparatively recent years, though the plant has been cultivated since prehistoric times in tropical Asia. The cereals and also sugar are the basis of many alcoholic products, much used in the industries and for beverages. Lawns and the greensward of parks are nearly always made up of grasses. In this country the most important lawngrasses are Kentucky bluegrass and the bentgrasses (Agrostis) for the northern States and Bermuda grass for the South. Various forms of creep- ing bent (Agrostis palustris), colonial bent (A. tenuis), and velvet bent (A. canina) are, in recent years, proving valuable for putting greens on golf courses. Though grasses play a minor role among ornamental plants, plumegrasses (pampasgrass, Ravenna grass, eulalia, and giant reed) are often used in parks to form large showy clumps. Although bamboos are not very familiar in this country, they enter largely into the life of the peoples of tropical regions, espe- cially in Asia. Some primitive peoples there use them not only for houses, but for practically all household utensils. RECENT PROGRESS IN AGROSTOLOGY Our knowledge of grasses is increased by observations made upon living plants as they grow in their native habitat, by studies of dried specimens in herbaria, where plants from different regions may be compared, and by anatomical investigations with the microscope in the laboratory. A recent expedition to Brazil has resulted in important additions to our knowledge of that region. Jason R. Swallen, assistant agros- tologist, spent 8 months in northeastern Brazil, studying and col- lecting grasses for the National Herbarium. He visited the states 32 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 of Para, Maranhao, Piauhy, Ceara, and Rio Grande do Norte, a part of Brazil in which few botanical collections, especially of grasses, have been made. In much of this area the chief means of transportation is by rivers which flow from south to north. To reach the grassy savannas of the interior Mr. Swallen was obliged to travel hundreds of miles on muleback. The result was a fine col- lection of grasses now being studied at the National Herbarium. The notes on habit, distribution, and habitat are important aids in determining the systematic relation of the species. The collections made by trained agrostologists are especially val- uable additions to the section of grasses of the National Herbarium, which now contains the largest number of specimens of grasses of any herbarium in the world, the number of sheets being more than 210,000. The classification of plants is an attempt to show systematic or genetic relationships. In many cases the relationship is obvious, but there are groups which cannot be placed with assurance in a system of classification. Not infrequently the systematic position of a genus (for example) is clarified by a study of developing organs, the inter- nal anatomy of tissues, or the germination of the seeds. Recently, there has been published a work ? which bears strongly on the classi- fication of grasses. By a microscopical study of the early stages in the development of the inflorescence of certain grass genera (Setaria, Pennisetum, Cenchrus), Dr. Arber has shown the morphological similarities of the bristles, spines, and involucral bracts which at maturity appear so diverse. She has investigated the rhizomes of bamboos, the corms of Arrhenatherum elatius var. bulbosum, and the inflorescence of Hordewm. She reviews the work done upon Indian corn or maize by Collins and others in this country and adds many observations of her own upon this remarkable grass. Spartina townsendti (see p. 303) has received her attention, and she lends the weight of her opinion to the theory that the species is of hybrid origin. Many other morphological puzzles have been studied in this important book. 2 Arber, Agnes, Gramineae, a study of cereal, bamboo, and grass. Cambridge Uni- versity Press, 1934. PLATE 1 Smithsonian Report, 1934.—Hitchcock g t= h into dry land. rass, Indian rice (Zizania aquatica), which is helpin to convert a mars 1. A marsh g Locally St. Croix, West Indies. ipted to dispersal by the wind. iil (Andropogon bicornis). € ass with fluffy seeds ad A gr known as foxt 9 PLATE 2 Hitchcock Smithsonian Report, 1934. t os =o an stern United States, pikelets can be seen anks on a central axis ce see 2 CE oss ae 7 mae *SSBId BAN SB Sesnoyusddis UL peyVAnyyno Alpe ISBOOQ = *SUTeJUNOUT 98y4 siojue ‘Sepuy 9} Jo odojs U194sve oY] UO ‘NJoeg ‘aueteg BIMOTOD IE SB OJIN OF [INbexens) uO’ pRosres ayy SUOTY ‘Seoe[d 4stour ur IWIN *(WnzojLbvs WNLdIUA) SSBIS BANJO SjURId o[SsUIg °Z SJOYOIY] OSUOP SUTUIIOY (LUNIDPUHDS WNLLIUA) SsBisouin[d osiKy y *T 3aLV 1d 3PODYPUFY—"p EG] ‘J4odayy ueiuosyyIWIG Smithsonian Report, 1934.—Hitchcock PLATE 4 1. A lawn of Kikuyu grass (Pennisetum clandestinum), Nairobi, Kenya. Residence of the Governor. This grass is now being tried in southern United States and gives promise of success. 2. Bunch grasses, mostly ichu (Stipa ichw), on the high plain of central Peru near Chuquibamillo, altitude about 13,000 feet. At the onset of snow squalls the young lambs immediately take refuge beneath their mothers. ‘oyouod *Sd0.1} JOJO 4SOur T9[OOM GATIVU [BNSN OY} SIBOM OPIN OY, “AOpenory ‘ozvioquiiyo OYI[ JOJOUIBIP UL OSBaIOUL JOU OP SsoOquIvA JO SUIEJS OY, “WMO qunoyy IvoN ‘“paevoqd & Sururioy "no pousy A[[NJ USA Oq [[IAM JI SV JOJOUIVIP UI OSIVI Sv ST PUB SOTIOZIYI WOT -Ied 918 SUIOIS BBIRT BY, “ps meq J 9 1193S SuNOA oY, “ynoids wv suIMOoYsS 00 3g Jo duinypo y ‘tT AaLvV1d 3P0IYINF{—"pEG| ‘10dayy ueruosy UWS Smithsonian Report, 1934.—Hitchcock PEATE 6 1. Great Plains near Amarillo, Texas. In this semiarid region the “short grasses "” are in bunches with unoccupied areas between and do not form a continuous turf. Mostly species of Aristida. 2. A peculiar tussock grass (mossgrass, Aciachne pulvinata) which forms dense hard bunches scarcely to be recognized as a grass. Hills around Cerro de Pasco, Peru; altitude about 14,500 feet. Smithsonian Report, 1934.—Hitchcock PLATE 7 1. Grasses growing on rocks, the soil accumulating in crevices. A ridge of rock between the quarry and the Inca fort, north of Cuzco. The grooves appear to have been made by the dragging of the stones over the ridge. 2, A typical mountain bunch grass. Mount Chimborazo, Ecuador, altitude about 15,090 feet. The spaces between the bunches (species of Festuca) are fully occupied by other plants. Bog with tussock plants in foreground. = “Teg ‘00ZNO JO y4I0U ‘oquIL}AL{URI[O SS es IBON ‘pasiei atom sdoro yoy Ul peoe[d sem [IOS poos s[TTea otf} U9IMIOd Bole [OA] YOV UT ‘svouT oy} Aq opeUL o1oM (PouInI ‘“Openog ‘SouUB_ IWAN ‘SYI[O [BOT]JOA WO SUIMOIS sessBayH ‘7 Al[erjivd Mou) seovise} ey, “SYoOI uO ouL0Y We ore yeYY SOSSBID 'T aLvid PO IE{—"pE6| ‘qodayy uetuosyysws PHOTOTROPISM: A SPECIFIC GROWTH RESPONSE TO LIGHT By Ear 8S. JOHNSTON Division of Radiation and Organisms, Smithsonian Institution [With 2 plates] Psychologists and physiologists have shown that the human eye is most sensitive to yellow and becomes less and less sensitive to ight of longer and shorter wave lengths as one passes toward the red and the blue, respectively, of the visible spectrum. In other words, when all the colors of the spectrum are of equal intensity, yellow looks the brightest to the human eye. Of the entire range of radiant energy, only that falling between the approximate limits 4,000 and 7,600 angstrom units is visible to the average human eye. However, longer radiation in the infrared can be detected by a sensation of warmth on the skin, and if the skin is exposed to certain short radiations in the ultraviolet, a temporary burning results. Experiments with animals such as the honeybee and a number of unicellular organisms have shown other ranges of sensitivity than that found in man. The question arises: To what wave lengths of radiant energy are plants sensitive ? There are a number of structures in plants which distinctly indicate a mechanism that responds to light. In certain dimly lighted caverns there is found a small moss, Schistostega osmundacea, whose proto- nema consists of a layer of lens-shaped cells so constructed that hight gathered over a relatively large area is concentrated onto a few chloro- plasts located in the bottoms of the cells. In the leaf cells of other plants the chloroplasts arrange themselves differently under different light intensities. The chloroplasts are the small bodies in green plants that bear the chlorophyll, the substance essential to life. When the hight is weak, these chloroplasts spread out at right angles to the rays of light and are thus able to intercept more light. If, however, the light is very strong, these same chloroplasts arrange themselves along the cell walls that are parallel to the light rays, thus intercepting a small fraction of the light. Another light-response reaction with 313 314 |§ ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 which everyone is familiar is the bending toward the light of common house plants that are grown on window ledges. The necessity for turning them from day to day in order to have them grow symmetri- cally is common knowledge. All these examples illustrate the fact that plants are sensitive to ight and that they have a definite light- response. The lop-sided growth of a potted window plant such as a geranium is an indication that the external conditions conducive to growth are not symmetrical. Although the temperature and humidity of the air may be the same on all sides of the plant, the light conditions are decidedly different. Those portions of the plant next to the window receive more light than those toward the darker interior, and the plant grows toward the more intense light. The phenomenon of unsymmetrical growth due to unilateral light conditions has been used by plant investigators to determine the sensitivity of plants to light. This response is known as phototropism. From a superficial observation it would appear that light hinders or retards elongation of plant cells. It is frequently noted that the stems of many plants grow more rapidly at night than during the day. Potatoes send forth greatly elongated shoots in a darkened cellar; if these same potatoes were permitted to remain in strong light, the sprouts would be very much shorter and the internodes greatly reduced. In the case of plants illuminated on one side it is noted that the shaded sides of the stems have stretched more than those receiving direct illumination. The uneven rate of growth on the opposite sides results in curved stems and a general appear- ance of the plant turning toward the light. Although superficial observations clearly indicate that the sensitiv- ity of the plant toward radiant energy is such that it reacts differ- ently to light and darkness, the question as to its sensitivity to dif- ferent colors or wave lengths of light is not so readily answered. To obtain an answer a plant might be placed half-way between two equally intense lights, for example blue and green, to ascertain to- ward which one the plant bends. The plant’s sensitivity to different colors could thus be determined in a general way and compared to * the sensitivity of various animal reactions or even to human vision. There is abundant evidence that phototropism is a special case of the more general light-growth phenomenon in plants, and that in- tensity as well as wave length and duration of radiation must be carefully considered. In phototropic experiments the specific char- acteristics of the plant must be known. The regions sensitive to light are frequently localized. The plant’s response is sometimes positive, that is, bending toward the light; sometimes negative, bending away from the light, and again it may even change from positive to nega- PHOTOTROPISM—JOHNSTON 315 tive. Furthermore, it has been shown in recent years that there are present in the plant specific growth substances which are directly associated with this light-growth response. The foundation of much of the recent work on phototropism was laid by the Dutch investigator, Blaauw. Perhaps the first quantita- tive measurements and physical interpretations were made by him and published in 1909. The responses of young seedlings were stud- ied in different regions of the spectrum, and the energy values were calculated from Langley’s tables. For oat seedlings Blaauw found the most effective region of the carbon arc spectrum to le between 4,660 and 4,780 A, whereas the red and yellow regions were ineffec- tive. The minimum amount of radiation required to produce photo- tropism was 20 meter-candle seconds. Furthermore it appears that for equal effects the product of light intensity and duration of ex- posure is a constant. Dillewijn, another Dutch investigator, has shown in a very inter- esting manner that the phototropic response of a plant can be pre- dicted by knowing how it grows in light of different intensities. He thus shows that phototropism is a light-growth response, as brought out by Blaauw’s theory. Using oat seedlings, Dillewijn determined the rate of growth in several different “ quantities ” of light and also for those of one-thirtieth the value. He had calculated that the light falling on one side of a seedling was reduced to one-thirtieth of its intensity after passing through to the opposite side. This value, of course, varies with the plant used. The results of Dillewijn’s experiments are reproduced in figure 1. The abscissa represents time in hours, and the ordinate the rate of growth expressed as » per minute (u=0.001 mm). The light intensity is indicated on the right in meter-candles. The arrow represents the time of illumination, with the duration noted above in seconds. Each pair of curves represents two light “ quantities ”, one one- thirtieth of the value of the other shown as the lightly and heavily drawn lines, respectively. In the d pair of curves the side of the seedling next to the source of illumination (heavy line) is retarded more than the far side (light line), which results in a positive bending for this weak light quantity (80 and 2.5 meter-candles for 10 seconds). With a greater quantity of hght (2,400 and 80 meter- candles for 10 seconds), as illustrated by the pair of curves in @, first a positive then a negative bending would occur. eee - Rae OG Na 2. ‘‘KILLED’’ VESSELS FROM ENGLEWOOD MOUND. 3. SAND MOUND ON CANAVERAL PENINSULA. Smithsonian Report, 1934.—Stirling PLATE 4 1. CROSS-SECTION OF MOUND C SHOWING SUPERIMPOSED TEMPLE FOUNDATIONS. MACON GROUP. Note aboriginal stairway approach in right-hand corner. 2. CROSS-SECTION OF MOUND D SHOWING HORIZONTAL CORN ROWS RUNNING UNDER MOUND. MACON GROUP. Smithsonian Report, 1934.—Stirling PLATE 5 1. INTERIOR RECONSTRUCTION OF MACON COUNCIL HOUSE. From drawing by F. C. Etheridge. 2. HYPOTHETICAL RECONSTRUCTION OF MACON COUNCIL HOUSE. From drawing by F. C. Etheridge, Smithsonian Report, 1934.—Stirling PLATE 6 1. STONES SERVING AS FOUNDATION FOR WALLS IN PEACHTREE MOUND, NORTH CAROLINA. 2. STONES REMOVED SHOWING PREPARED FLOOR. NOTE SMALL COMPARTMENT WALLS ABOVE FLOOR. PEACHTREE MOUND. Smithsonian Report, 1934.—Stirling PLATE 7 1. BURIAL BENEATH BASE OF PEACHTREE MOUND WITH SHELL BEADS AND TWO- WOODEN EAR ORNAMENTS COVERED WITH COPPER. 2. INTRUSIVE STONE-LINED GRAVE IN PEACHTREE MOUND. PLATE 8 Smithsonian Report, 1934.—Stirling EXPLORATORY TRENCHES BETWEEN ABORIGINAL MOUNDS, SHILOH NATIONAL PARK, TENNESSEE ite , SHILOH NATIONAL PARK. SECTION OF BURIAL MOUND 2 Smithsonian Report, 1934.—Stirling PLATE 9 1. FLOOR PLAN OF YOKUTS’ HOUSE SHOWING POSTHOLES AND FIREPLACE. TULAMNIU, MOUND 1, CALIFORNIA. 2. BURIAL OF CHILD WITH TWO STEATITE BOWLS, TULAMNIU, MOUND 1. Smithsonian Report, 1934.—Stirling PLATE 10 1. HOUSE FLOORS, FIREPLACES, AND COOKING PITS EXPOSED AT MOUND 2, TULAMNIU. Many of the cooking pits had later been used for burial purposes. 2. NEW TYPE ‘‘STRATAGRAPH’’ USED IN MAKING RAPID AND ACCURATE DIAGRAMS OF DEEP STRATA AT TULAMNIU. INDIAN CULTURES OF NORTHEASTERN SOUTH AMERICA By Hersert W. KRIEGER United States National Museum [With 12 plates] NATIVE TRIBES AND LANGUAGES Indian tribes occupying northeastern South America come roughly within a grouping consisting of four large linguistic stocks—the Tupi, the Tapuya, the Arawak, the Carib—and of several smaller ones. The checkered geographic arrangement of two of these, the Arawak and Carib in northern South America, east of the Andes, is remarkable. Various theories have been developed to account for this. The most widely accepted and most plausible theory, although not necessarily the most correct one, is that as the Caribs were war- like and the Arawaks peaceful, they were continually engaged in warfare and migrations, with the Arawaks in the lead closely fol- lowed by marauding bands of Caribs. Perhaps the only authority for this is observations made by Spanish explorers on the Lesser An- tilles at the time of their discovery, when the Caribs were actively on the trail of the Arawaks, dispossessing them of their women and driving them out of their island homes. At this time, so it is con- jectured, the Caribs had supplanted the Arawaks in the Lesser An- tilles, an island archipelago which extends all the way from the delta of the great Orinoco River, and the outlying island of Trinidad in the Gulf of Paria on the Venezuelan coast, to Vieques just east of Puerto Rico. Undoubtedly several explanatory factors in addition to the harass- ment of war should be taken into consideration in accounting for the widely scattered Arawak and Carib tribes in the South American mainland north of the Amazon. Many of the early documents and narratives treating with tribal distribution in tropical South America refer to tribes no longer occupying the areas mentioned in those accounts. In other words, the displacement forces are still at work. 401 402 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 Most of the tribes of the tropical rain forests, savannas, and coastal plains practice a tropical agriculture based on cassava, but are at the same time seminomadic hunters and fishermen. Milpa agriculture, or the planting of root crops in a forest clearing which is abandoned after a few seasons, would alone suffice to account for extensive tribal wanderings in the course of a century. The distribution of Indian tribal stocks in northeastern South America is not well known. The field is a large one, larger than the entire area of the United States including Alaska, and the native population is widely disseminated. The accounts of early explorers, often the only source material available, remain uncorrected as to details but are authoritative within a broad outline. The researches of noted scholars in the area, such as Koch-Gruenberg, Lehmann- Nitsche, Chamberlain, Nordenskiold, Von den Steinen, Farabee, Fewkes, Stirling, Karsten, Krause, Rivet, Von Rosen, Schmidt, Steere, Jahn, Joyce, DeBooy, Im Thurn, Roth, Brett, Lange, Linné, Netto, Hartt, Pinot, Ernst, Church, Von Ihering, Ehrenreich, Géldi, Petrullo, and Brinton, have determined within broad outlines the linguistic, cultural, and geographical boundaries of the more compre- hensive groups. ETHNIC MAPS An excellent map of the “Country and Environs of the Guiana Indians ”, appearing in the 38th Annual Report of the Bureau of American Ethnology, was compiled by Dr. W. E. Roth from the maps of Crevaux, Condreau, Schomburgk, Koch-Gruenberg, the Venezue- lan War Department, and the Mission Bresilienne d’Expansion Economique. There is also a tribal map covering all of South America in “ The American Indian”, by Clark Wissler. This map is based on original sources and brings out the relation of the tribes to the larger linguistic groups perhaps more clearly than in the origi- nal sources. Chamberlain’s “ Linguistic Stocks of South American Indians ”, published in the American Anthropologist (n. s., vol. 15, no. 2, April-June 1913), has a distribution map extensively used as a source reference. The excellent tribal distribution map appearing in Buschan’s “ Voelkerkunde ”, Stuttgart, 1922, was carefully com- piled by Dr. Krickeberg, and is based on the work of Chamberlain, Koch-Gruenberg, Lehmann, Rivet, Outes, and Joyce. The map ac- companying this paper is an adaptation of the Roth and Buschan maps. In it an attempt is made to outline tribal as well as linguistic areas. The topography of northeastern South America is simple, con- sisting of highlands in the southern and eastern portions of Brazil and surrounding low plains. To the northwest the low-lying country drained by the Orinoco and by the Amazon and its tributaries is SOUTH AMERICAN INDIAN CULTURES—KRIEGER 403 covered with a dense forest; the lowlying plains on the southeast are periodically inundated when the Uruguay and Parana Rivers Wsr wucia ZST VINCENT TRIBES AND LINGUISTIC STOCKS OF SOUTH AMERICA SOOMILES TO ONE INCH ° 400 600 wus COMPILED BY HERBERT a KRIEGER TOR & L) (iz lg ag =A l a \guetrual TTY BEERS sR aa Yd r 3 ze Seance! aa eee . = ~ > = > =< ” Bees Zz (9) ae _NVINOSHLINS SS!YVYUEIT LIBRARIES INSTIT! = sf Z a Zz n ex! on a) on zi: o pe oe ps a SN a ra pa m “” m i = wn = 7) SMITHSONIAN INSTITUTION NOILNLILSNI NVINOSHLINS S3ItuV NVINOSHLINS SZ1uVe w ae 2 y, z 2 ec Ny 4 iL Yop, Zz a Sf peer eee =: - \ = = 5 _NVINOSHLINS SSINVEYSIT_LIBRARIES SMITHSONIAN _INSTIT\ 2% 8 : : 2 WW: = a = SNS" in a = ao) eee = = zz a = S IBRARIES SMITHSONIAN INSTITUTION NOILALILSNI NVINOSHLIWS S31uV = ae = oe z = oO ve ) Be os = KX ES aD | e > =) ‘ ? = Be 0 ei \ ae i ~ a a = 7) rm ce) ‘& A) Z wo Zz ieee JLNLILSNI SSIYVYEIT LIBRARIES SMITHSONIAN NVINOSHLINS S31uvVudl) LIBRARIES NVINOSHLIWS NSS “Y SMITHSONIAN : * IBRARIES SMITHSONIAN - INSTITUTION NOILALILSNI NVINOSHLINS SAIYV SMITHSONIAN SMITHSONIAN NOILNLILSNI LIBRARIES S3iY¥VYEIT LIBRARIES SMITHSONIAN _INSTITt SSAtavVdadli LIBRARIES INSTITUTION INSTITUTION NOILNLILSNI STINVUGIT- LIBRARIES SAaluVvadly INSTITUTION NOILNLILSNI NVINOSHLINS SAIluV oY zz a) z no = =e = = = jy = 5 \ = S = YJ WA 3 St BN fe) a5 fe) \ — = WS SS =, = a “si ss W 2 SX is = BANS > = > < w - Zz rT) Be OILALILSNI NVINOSHLINS S3IYVYS!I1 LIBRARIES SMITHSONIAN iNSTITL 2 a z= n = a - @ “ir 2 LASS < = z BL = a = SS a A ca e F fe ¥; S S ae — Oo ey 5 5 re = os = IBRARIES, SMITHSONIAN INSTITUTION NOILNLILSNI NVINOSHLINS SALUV i z 8 ocr = i se a = » : pd SAS vw Las St 8 Oe as SO OS